Compliant fixation of external prosthesis

ABSTRACT

A fixation device and method for attaching an external prosthesis to a bone. The fixation device includes a main body having a compliant portion operable to be expanded and contracted. The main body has a first end fixedly retained in the bone and a second end coupled to an extension for receiving the external prosthesis. The main body and the extension define respectively first and second engagement surfaces for constraining a bone graft therebetween.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Ser. No. 10/305,620,filed Nov. 27, 2002 now U.S. Pat. No. 6,712,855, which is a continuationof U.S. Ser. No. 09/776,584, filed Feb. 2, 2001, now U.S. Pat. No.6,508,841 which is a continuation of U.S. Ser. No. 09/003,061, filedJan. 5, 1998, now U.S. Pat. No. 6,197,065, which is acontinuation-in-part of U.S. Ser. No. 08/535,532, filed Sep. 28, 1995,now abandoned, which is a continuation-in-part of U.S. Ser. No.08/146,510, filed Nov. 1, 1993, now abandoned. The disclosures of theabove applications are incorporated herein by reference.

INTRODUCTION

In prosthetic segmental bone replacements, it is sometimes necessary toreplace a portion of a long bone to correct various types of bone injurysuch as those caused by bone tumors, osteoarthritis, fracturedislocations, rheumatic arthritis, and aseptic or a vascular bonenecrosis. In these types of surgical procedures, it is necessary toresect a mid and/or end portion of a long bone and secure the remainingportion of bone through the use of some type of intramedullary device.This is accomplished by the use of one metal stem, or in certain cases,two opposing metal stems, secured in the medullary region by a “bonecement” or a grout material, such as methylmethacrylate.

Biologic fixation of intramedullary devices at the mid-diaphyseal levelhas not been entirely satisfactory, particularly in active youngerpatients, where it is important to form a stable, long-lastingprosthetic attachment. In time, the lack of adequate stress transferfrom the metal stem to the surrounding bone causes a loss of bonedensity, resulting in increased possibility of bone failure or looseningof the bone-stem interface. Also, the bone reacts in the grout materialor smooth metal stem by forming a soft-tissue lining around the cement,and this lining additionally mediates load transfer from the prostheticdevice to the bone. The soft-tissue lining that forms about the devicetends to loosen over time, particularly with continued shear loads,i.e., loads applied substantially in the direction of the axiallyextending bone/stem interface, and the loosening may become great enoughin time to require surgical revision. Also, the relatively low toleranceof force transfer per unit area of interface requires a large bone/steminterface, which, in younger patients, may exceed the availableinterface area.

In replacement surgeries, which begin at the mid-diaphyseal level, theenlarged intramedullary cavities created within a remaining diaphysealbone portion for the insertion and rigid fixation of a metalintramedullary device stem is also of small diameter. As a result, thedevice stems must be of a small diameter to fit within the diaphysis,with resulting poor rotational control. Also, high bending moments inthin stems at the mid-diaphysis risk fatigue failure, making a stableinterface between the stem and the surrounding bone surface even moredifficult to achieve.

Although the use of a tapered stem is one way to achieve increasedsecurity of the stem within the medullary canal, the canal dimensionstend to increase rather than decrease with increasing depth into thecanal, thereby preventing secure wedging of a tapered stem.Consequently, “bone cement” or grout fixation is often used to securethe stem within the medullary canal. This technique, however, preventsstress transfer through the bone to the level of the osteotomy,therefore resulting in osteopenia adjacent to the stem. The same effectprevents bony ingrowth into porous pads on the shoulders of theimplants. A limitation of prosthetic devices which rely on biologicalfixation, particularly fixation to an elongate stem within theintramedullary region of a bone, is the problem of stress protection ofthe bone region between the area of force application to the prosthesisand the area of load transfer to the bone. Stress protection is due tothe rigid attachment between the prosthetic device and bone which occursin biological fixation and to the relatively high elastic modulus of theimplant material, which typically is five to fifteen times greater thanthat of the surrounding bone. These two factors combine to transfer astress from the area of stress loading on the implant through the morerigid implant, rather than through the surrounding bone tissue. Forexample, in a hip-joint prosthesis biologically anchored to the bone byan entire elongate stem, axial stress on the upper joint is transferredlargely through the stem to the bone connection farthest from the joint,rather than through the intermediate bone region surrounding the part ofthe stem closest to the joint. As a result, the intermediate bone regiontends to be resorbed over time due to lack of deformation stressing. Thegradual loss of bone support in the region of the stem increases thebending load that must be borne by the stem, and this can lead toimplant fatigue and failure.

The problem of maintaining a motionless bone-prosthesis interface duringthe post-operative period when bony attachment is occurring may bepartially solved by surgically fastening the prosthetic device to thebone structure by screws or the like. This method has been proposed foruse in fastening a knee-joint prosthesis to a surgically formed,substantially planar surface of the bone. Typically, the prosthesis isattached by two or more screws, each tightened to hold the prosthesisagainst the bone surface with a selected compression. However, since thebone quickly accommodates to the applied force of the screws, byviscoelastic creep, the compression, and thus the resistance to theimplant movement relative to the bone, is quickly lost. If interfacemovement does occur from a single episode of overloading, then anyresidual compression is permanently lost. More movements result inbuild-up of fibrous tissue, preempting biological bone fixation to theimplant. Only with unphysiologic post-operative protection of the joint,resulting in joint stiffness and muscle wasting, and with demandingoperative technique, can risk of loosening be reduced. The device alsosuffers from problems of stress protection and non-physiological loadtransfer, inasmuch as loading force applied to the prosthesis istransferred directly through the screws, rather than through the regionof bone through which the screws extend. This can lead to loss of boneintegrity in the stress protected area.

The problems associated with anchorage via soft tissue along aprosthesis stem have been overcome partially by using a prosthesis whosestem surface allows direct attachment without an interposed soft tissuelayer. Such surfaces include micropore surfaces that allow attachmentvia ingrowth and/or attachment of bone, and ceramic surfaces that allowactual bonding of bone. Following surgical implantation of the stem, thesurrounding bone tissue gradually forms a biological fixation matrixwith the stem surface by tissue growth into or onto the surface. Becauseof the stronger interface between the bone and the stem, which allows arelatively large force per unit area without loosening, problems of lateloosening and detachment are largely avoided and the force transfer areacan be made smaller.

A limitation of the biological-fixation bonding approach, however, isthe need to keep the prosthesis mechanically fixed with respect to thebone over a 2–3 month post-operative period, during which the biologicalfixation is occurring. If relative movement between the implant stem andbone is allowed to occur before biological fixation is complete, afibrous tissue layer which acts to prevent good biological fixationdevelops at the interface and eventual progression to gross loosening islikely.

Another shortcoming resulting from bone replacement surgeries,particularly joint replacement procedures, is a phenomenon known as wearparticle bone lysis. The replacement of a joint, including theinstallation of a polyethylene or similar high molecular weightsynthetic wear surface, results over time in particles becomingdislodged from the wear surface due to friction between the jointsections during movement. These wear particles tend to move with fluidtransfer along the interface between the prosthesis and the surroundingsoft tissue, and also tend to enter the intramedullary space between theprosthesis stem and the surrounding remaining bone portion. Thebiological reaction to these small wear particles causes the surroundingbone tissue to be lysed, thereby weakening the bone and potentiallycausing subsequent bone failure. Thus, a means for sealing theintramedullary space from the exterior space could largely reduce thisdifficulty.

Prosthetic devices having spring-loaded mechanisms for holding ajoint-replacement prosthesis against a planar surface of the bone, toimmobilize the prosthesis on the bone, have been proposed, e.g., in therelated field of joint replacements, such as in U.S. Pat. No. 4,129,903.Devices of this type solve some of the above-noted problems associatedwith prosthesis attachment to the bone, in that the prosthesis is heldagainst the bone under relatively constant tension in the post-operativeperiod, with or without provision for biological fixation. Nonetheless,limited movement may occur when the major loading stresses (in theprincipal direction of weight transfer on the joint) are not normal tothe plane of the interface between the bone and prosthetic device and itis necessary to rely on a grouting compound to prevent shear motions.Further, such devices use a rigid stem or shaft for anchoring theimplant to the bone traversed by the stem from physiologic shear,rocking, and/or axial rotation stresses.

Each of these potential problems may limit physical activity andlong-term durability prognosis for long segmental replacementarthroplasty patients. Thus, current methods may potentially result inrepeat surgeries which leave less bone stock and may eventually requireamputation or other undesirable salvage procedures.

For the above reasons, it is desirable to provide a segmental bonereplacement device which enhances a stable biologic fixation, yet allowsfor physiologic cyclic load transfer to the device-bone interface. It isalso desirable to provide a device which promotes osteogenesis intothose surfaces adjacent to the osteotomy. It is also desirable toprovide a fixation device for attaching an external prosthesis to abone.

SUMMARY OF THE INVENTION

The present teachings provide a fixation device for attaching anexternal prosthesis to a bone. The fixation device includes a main bodyhaving a compliant portion operable to be expanded and contracted. Themain body has a first end fixedly retained in the bone and a second endcoupled to an extension for receiving the external prosthesis. The mainbody and the extension define respectively first and second engagementsurfaces for constraining a bone graft therebetween.

The present teachings also provide a fixation device for attaching anexternal knee prosthesis to a distal femoral bone having an attachedpatella. The fixation device includes a main body having a superiorshoulder and operable to engage a prepared femoral surface. An extensionis coupled to the main body with a taper to taper connection. Theextension includes a inferior ring, and the inferior ring and thesuperior shoulder are configured to constraint the patella therebetween.An anchor can be coupled to the main body and is operable to be fixedlyretained within the femoral bone. A compliant portion operable to beexpanded and contracted can be disposed between the body and the anchor.

The present teachings also provide a compliant fixation device forattaching an external prosthesis to a bone having an attached bonegraft. The fixation device includes first and second engagement surfacesfor constraining the bone graft therebetween.

The present teachings provide a method for attaching an externalprosthesis to a bone, such as distal femur, having an attached bonesegment, such as patella. The method includes anchoring a first end of acompliant fixation device to a cavity formed in the distal femur,constraining the patella between first and second engagement surfaces ofthe fixation device, and suturing femoral skin on a second end of thefixation device.

Additional objects, advantages, and features of the present inventionwill become apparent from the following description and appended claims,taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The various advantages of the present invention will become apparentfrom the following specification and appended claims by reference to thefollowing drawings in which:

FIG. 1 is a partial cut-away view illustrating the environment of thedevice of the present invention in connection with a remaining boneportion following resection;

FIG. 2 is an enlarged cross-sectional view illustrating a boneattachment device as it is secured within a remaining bone portionfollowing resection;

FIG. 3 is a cross-sectional view illustrating one embodiment of ananchor body secured within a cavity of remaining bone portion;

FIG. 4 is a cross-sectional view illustrating the upper compliantportion of the bone attachment device of the present invention;

FIG. 5 is a top view illustrating a portion of the device shown in FIG.4, taken from the perspective 5—5 in FIG. 4;

FIG. 6 is a bottom view illustrating the compliant section of the boneattachment device of the present invention, taken from a perspective 6—6in FIG. 4;

FIG. 7 is a cross-sectional view illustrating a bone attachment assemblyof the present invention which includes fluid sealing means for reducingaccess of wear particles;

FIG. 8 is a perspective view illustrating a guide device for creatingone or more apertures within a remaining bone portion for accepting oneor more engagement means;

FIG. 9 is a side view illustrating a self-centering drill bit of thepresent invention;

FIG. 10 is a partial cut-away view illustrating a milling device usedfor milling the osteotomy surface in a preselected geometry;

FIG. 11 is a partial cut-away view illustrating a milling device usedfor milling the osteotomy surface in a preselected geometry;

FIG. 12 is a cross-sectional view illustrating a bone attachment devicein conjunction with an orthopedic appliance;

FIG. 13 is a cross-sectional view illustrating a percutaneous barconnected to a device of the present invention;

FIG. 14 is a perspective view illustrating a reaming device of thepresent invention;

FIG. 15 is an elevational view with partial breakaway illustrating theenvironment of a second embodiment of the bone attachment assembly ofthe present invention in an implanted condition in connection with aremaining bone portion following resection;

FIG. 16 is an elevational view with partial breakaway illustrating asecond embodiment of bone attachment assembly of the present invention,prior to preloading the assembly;

FIG. 17 is an elevational view with partial breakaway illustrating thebone attachment assembly shown in FIG. 16, during preloading of theassembly;

FIG. 18 is an elevational view with partial breakaway illustrating theenvironment of a second embodiment of the bone attachment assembly ofthe present invention from a perspective 90□ removed from that shown inFIGS. 15 through 17, in a preloaded implanted condition in connectionwith a proximal femur prosthesis;

FIG. 19 is an elevational view with partial breakaway illustratinganother version of a second embodiment of the bone attachment assemblyof the present invention, prior to preloading;

FIG. 20 is an end view illustrating the bone attachment assembly shownin FIG. 19;

FIG. 21 is an elevational view with partial breakaway illustrating thebone attachment assembly shown in FIGS. 19 and 20 in a preloadedcondition;

FIG. 22 is a side cross-sectional view illustrating the version of thesecond embodiment of the bone attachment assembly of the presentinvention shown in FIGS. 19 through 21 in an implanted condition inconnection with a primary hip prosthesis;

FIG. 23 is a side elevational view illustrating the bone attachmentassembly of the present invention shown in FIG. 22 from a perspective90□ removed from that shown in FIG. 22;

FIG. 24 is an elevational view illustrating another version of thesecond embodiment of the present invention;

FIG. 25 is a top view of the version of apparatus shown in FIG. 24;

FIG. 26 is an elevational view in partial breakaway illustrating anotherversion of the second embodiment of bone attachment assembly of thepresent invention, in modular form;

FIG. 27 is an elevational view illustrating a first version of a thirdembodiment of bone attachment assembly of the present invention,including a main body and an anchor body with integral compliantsection, in exploded form;

FIG. 28 is a top view illustrating the main body component of the boneattachment assembly shown in FIG. 27;

FIG. 29 is a side view of an anchor body with integral compliantsection, from an angle 90□ removed from the angle shown in FIG. 27;

FIG. 30 is a partial cross-sectional view illustrating insertion of acompliant section of the bone attachment assembly within a sleeve formedas part of the main body shown in FIG. 27;

FIG. 31 is a partial cross-sectional view illustrating a main body withintegral sleeve and anchor body with integral compliant section,disposed upon and within a remaining bone portion, with the anchor bodysecured to the surrounding bone cortex prior to the application oftraction to the compliant section;

FIG. 32 is an elevational view in exploded form illustrating a secondversion of the third embodiment of the present invention, including amain body and anchor body with integral compliant section, in modularform;

FIG. 33 is a partial cross-sectional view illustrating the componentsshown in FIG. 32, in assembled form and disposed within a remaining boneportion, with secured anchor, with traction applied to the compliantsection, and with an intercalary segment attached thereto;

FIGS. 34, 35 and 36 are perspective views illustrating three differentsizes of an alternative configuration of anchor body and integralcompliant section, each having a tapered, self-tapping threaded section;

FIG. 37 is a bottom perspective view illustrating the cutting threadconfiguration for any of the anchor bodies shown in FIGS. 34, 35 or 36;

FIG. 38 is a perspective view illustrating a configuration of screw usedfor securing a main body to a compliant section integrally formed withan anchor body;

FIG. 39 is a partial cross-sectional view illustrating a main bodyattached through the use of the screw shown in FIG. 38 to a taperedthreaded anchor body and integral compliant section disposed within aremaining bone portion;

FIG. 40 is a partial cross-sectional view illustrating the attachment ofa tibial tray to an compliant section and integral threaded anchor body;

FIGS. 41, 42 and 43 are perspective views illustrating three differentsizes of specially-shaped tapered reamers for use in enlarging theintramedullary canal of a remaining bone portion for the insertion ofany of the tapered threaded anchors shown in FIGS. 34, 35 or 36;

FIG. 44 is a partial cross-sectional view illustrating the use of atapered reamer for enlarging the intramedullary canal of a remainingbone portion;

FIG. 45 is a partial cross-sectional view illustrating use of an anchorinserter and threaded rod assembly for accomplishing the insertion of athreaded anchor within a prepared intramedullary cavity of a remainingbone portion;

FIG. 46 is a partial cross-sectional view illustrating the use of aguide device for drilling apertures through the cortex of a remainingbone portion within which an anchor body of the cross-secured type isbeing installed;

FIG. 47 is a partial cross-sectional view illustrating the use of a facereamer for milling an interface surface of a remaining bone portion to apredetermined angle;

FIG. 48 is a cross-sectional view illustrating another version of boneattachment assembly of the present invention, having a convexlyexteriorly shaped main body shoulder portion;

FIG. 49 is an alternative version of the bone attachment assembly shownin FIG. 48;

FIG. 50 is an alternative version of the bone attachment assembly shownin FIGS. 48 and 49, with a sleeve disposed for inhibiting non-axialrelative displacement of the compliant section and main body;

FIG. 51 shows the version of bone attachment assembly shown in FIG. 48,installed within a proximal femur;

FIG. 52 is a partial cross-sectional view of a non-coaxial version ofbone attachment assembly;

FIG. 53 is a sectional view of a compliant fixation device for anexternal prosthesis according to the present teachings; and

FIG. 54 is an environmental sectional view of a compliant fixationdevice for an external prosthesis according to the present teachings.

DESCRIPTION OF VARIOUS EMBODIMENTS

It should be understood that while this invention is described inconnection with particular examples, the scope of the invention need notbe so limited. Rather, those skilled in the art will appreciate that thefollowing teachings can be used in a much wider variety of applicationsthan the examples specifically mentioned herein.

Referring now to FIG. 1, there is shown a bone assembly 10, whichincludes a first remaining bone portion 12 and a second portion 14, asis the case involving a mid-diaphyseal segment replacement. The secondportion 14 may be an orthopedic appliance, an orthopedic applianceconnected to a second remaining bone portion, or may be replaced by apercutaneous bar suitable for the attachment of an external appliance,as will be discussed below. The second remaining bone portion may be aportion of the same bone as the first remaining bone portion, or may bea portion of another bone.

The first remaining bone portion 12 is shown to include a firstintramedullary cavity 16, which is preferably an enlarged longitudinalcylindrically-shaped bore created to a preselected depth from theosteotomy surface. The first intramedullary cavity 16 may substantiallycoincide in its longitudinal axis with the natural intramedullary canalof the bone. In those situations where the second portion 14 is in theform of an orthopedic appliance connected to a second remaining boneportion, the second remaining bone portion may similarly include asecond intramedullary cavity (not shown), which may preferably besubstantially similar in size and shape to the first intramedullarycavity 16. Also, the means of connecting the second remaining boneportion may be entirely different from this arrangement, including theuse of bone cement or other suitable materials.

Disposed as a part of the bone assembly 10 is a biocompatible boneattachment assembly, shown generally at 18. The bone attachment assembly18, in a preferred embodiment, includes a first bone attachment device20, which is located about the first remaining bone portion 12. Thefirst bone attachment device 20 may be secured to the second portion 14through the use of a clamp 76, which is preferably of a type discussedbelow in connection with FIGS. 5 and 6. The bone attachment assembly 18may also further include a second bone attachment device (not shown)located about the second portion 14, in the situation where the secondportion 14 is a second remaining bone portion.

Referring now to FIG. 2, the first bone attachment device 20 isdescribed in greater detail. FIG. 2 is an enlarged cross-sectional viewillustrating a bone attachment device 20 as it is secured within thefirst remaining bone portion 12. The first bone attachment device 20 isshown to include a main body 22 which is constructed of a suitablebiocompatible material. Examples of suitable materials are titaniumalloys such as Ti-6Al-4V, CoCr (cobalt chromium) alloys and commerciallypure titanium. Other suitable materials may be used. It is preferredthat the components of the bone attachment assembly 18 be constructed ofthe same material. Preferably, the main body 22 is substantiallycylindrically-shaped, and may include a shoulder portion 24, at leastone pin channel 26 and a longitudinal bore 28. The main body 22 ispreferably operable to be positioned upon a milled end portion 30 of thefirst remaining bone portion 12. It will be appreciated that the mainbody 22 will replace a portion of the length of bone being removedduring the surgical procedure, by virtue of its position upon the milledend portion 30.

The milled end portion 30 is created in a preselected geometry relativeto the cylindrically-shaped first intramedullary cavity 16. Preferably,as shown in FIG. 2, the milled end portion 30 is formed to anaxisymmetric geometry, and most preferably to a convex conical geometry,whose cross-section has a preselected included angle of inclinationrelative to the longitudinal axis in the direction of the firstremaining bone portion 12. Other preselected geometries and angles mayalso be used. The main body 22 includes an interface surface 32 which ismost preferably constructed to substantially match the geometry of themilled end portion 30, thereby providing a substantially flush interfacebetween the milled end portion 30 and the interface surface 32. As such,the interface surface 32 may also be created in an axisymmetric orconcave conical geometry, or in another suitable geometry. The interfacesurface 32 is preferably operable for accepting biological boneattachment by bone ingrowth and/or ongrowth.

The main body 22 is shown to preferably include a cannulated stemportion 34, which is preferably in the form of a single unitarystructure. The cannulated stem portion 34 may be of a substantiallycylindrical shape, as shown in FIG. 1, or may be tapered along itslength at one of several selected major and minor diameterconfigurations, depending upon the diameter of the original naturalintramedullary canal of the bone and also upon the extent of reamingrequired in forming the first intramedullary cavity 16. Preferably, themajor diameter of the cannulated stem portion 34 is represented by acylindrical portion of the stem, which may fit with reduced lateralmovement against the walls defining the first intramedullary cavity 16.As shown in FIG. 2, the cannulated stem portion 34 may occupy asubstantial length of the first intramedullary cavity 16. The cannulatedstem 34 may be made from the same selection of materials as the mainbody 22. The cannulated stem portion 34 also includes a longitudinalbore 36 that is coaxial with the longitudinal bore 28 disposed throughthe main body 22. Preferably, the longitudinal bore 28 and thelongitudinal bore 36 are substantially identical in diameter and arerelatively positioned so as to form a single continuous bore.

The first bone attachment device 20 further includes means for anchoringthe device in an enhanced stationary position within the firstintramedullary cavity 16. The means for anchoring the first boneattachment device is shown to be in the form of an anchor body 38 whichis located within the first intramedullary cavity 16 at its distal end.The anchor body 38 may be made from the same material as the main body22. The anchor body 38 includes one or more apertures 40 that areoperable for accepting the insertion of one or more fixation devices.The apertures 40 may preferably be a plurality of staggered apertures ofsubstantially the same preselected diameter. One possible staggeredarrangement for the apertures 40 is the arrangement shown in FIG. 1. Itwill be appreciated, however, that any suitable arrangement for theapertures 40 may be used, including those wherein the apertures 40 arein perpendicular or other non-parallel arrangements.

To provide a passageway for the insertion of suitable fixation devicesto engage the anchor body 38, one or more fixation bores 42 are providedthrough the first remaining bone portion 12. The fixation bores 42 arepreferably sized and located to substantially match the size andlocation of the apertures 40 upon the anchor body 38. As such, thefixation bores 42 may also preferably be disposed as a plurality ofstaggered bores created through the first remaining bone portion 12.

The first bone attachment device 20 also includes one or more engagementdevices that are operable to provide an engagement between the anchorbody 38 and the first remaining bone portion 12, so as to enhance asubstantially secured relation of the anchor body 38 within the firstintramedullary cavity 16. In one embodiment, the selection of engagementdevice is one or more transverse pins 44 which traverse one or morefixation bores 42 on at least one side of the anchor body 38, and alsotraverse one or more apertures 40 disposed across the anchor body 38.Most preferably, a plurality of transverse pins are used in the samepreselected staggered arrangement as the apertures 40 and the fixationbores 42. The transverse pins 44 may be disposed in a substantiallyparallel relation, as shown. It will be appreciated, however, that thetransverse pins 44 may be disposed perpendicularly, or at otherpreselected relative angles.

The selection of engagement device may also be one or more ofinterlocking screws 46, as is shown in FIG. 3. FIG. 3 is across-sectional view illustrating one embodiment of an anchor body 38secured within the intramedullary cavity of a remaining bone portion.The interlocking screws 46, like the transverse pins 44, preferablytraverse one or more apertures 40 and one or more fixation bores 42. Theinterlocking screws 46 may be threaded from one side of the firstremaining bone portion 12, or may alternatively be threaded fromopposite sides. The interlocking screws 46 may also be disposedperpendicularly, or at other preselected relative angles. As before, theinterlocking screws 46 may be disposed in a staggered arrangement so asto enhance the stability of the anchor body 38 within the firstintramedullary cavity 16. The transverse pins 44 and interlocking screws46 may both be made from the same materials as the main body 22.

Referring again to FIG. 2, the first bone attachment device 20 isfurther shown to include means for attaching the main body 22 to themeans for anchoring the bone attachment device 20. The means forattaching the main body 22 is provided in the form of acylindrically-shaped connecting rod 48 that is sized to traverse thelongitudinal bore 36 of the cannulated stem 34 and the longitudinal bore28 of the main body 22, while moving freely longitudinally withoutsubstantial restriction from engagement with the cannulated stem portion34 and the main body 22. The connecting rod 48 may be made from the samematerial as the main body 22. The connecting rod 48 is operable to beinserted through the main body 22 and the cannulated stem portion 34 toan engagement with the anchor body 38, such that the connecting rod 48extends from the anchor body 38 through the milled end portion 30. Theconnecting rod 48 also includes a lower threaded portion 50 that isoperable to engage a correspondingly threaded bore 52 located in theupper portion of the anchor body 38. The connecting rod 48 may also beconveniently threaded over its entire length. The connecting rod 48 hasa degree of compliancy relative to bone in its construction, such thatits disposition alone between the main body 22 and the anchor body 38provides a compliant fixation between the main body 22 and the anchorbody 38.

As shown in FIG. 3, the means for attaching the main body 22 to themeans for anchoring the biocompatible bone attachment device 22 may beprovided as a connecting rod 48 that is an integral extension of theanchor body 38. As such, the connecting rod 48 also extends from theanchor body 38 through the milled end portion 30.

Referring now to FIG. 4, the means for attaching the main body 22 to themeans for anchoring the first bone attachment device 20 may also furtherinclude a supplemental interposed compliant device for enhancing thecompliance of the bone attachment assembly 18. The supplementalinterposed compliant device operates by biasing the connecting rod 48against the main body 22. FIG. 4 is an enlarged cross-sectional viewillustrating a portion of the first bone attachment device 20 of thepresent invention. The supplemental interposed compliant device may becontained within a cylindrically-shaped recess 54 located atop the mainbody 22, or may also be operable to abut against another suitablesurface of the main body 22. In some arrangements, the supplementalinterposed compliant device may project partially from within the recess54. The supplemental interposed compliant device preferably includes oneor more washer springs 56 positioned about the upper portion of theconnecting rod 48. As shown in FIG. 4, a plurality of washer springs 56may be oriented in adjacently opposite directions upon the connectingrod 48. It will be appreciated that other suitable biasing arrangementsmay be used.

The washer springs 56 may be made from the same materials as the mainbody 22 set forth above, or may also be made from a nickel-titaniumalloy, such as nitinol. The use of nitinol as a material selection forthe washer springs 56 tends to reduce the number of individual springmembers required. The washer springs 56 may be replaced, however, by atleast one compressible elastic cylinder made from a material selectedfrom the group consisting of plastics and polymers. A suitable selectionfor an elastic cylinder material is polyurethane.

In order to secure the washer springs 56 in a biasing relationshipbetween the main body 22 and the connecting rod 48, a spring biasingmeans is provided. The spring biasing means may serve the doublefunction of locking means, which may be a lock nut 58 which may beadvanced upon an upper threaded portion 60 of the connecting rod 48 atleast until it contacts the supplemental interposed compliant device.The lock nut 58 may be made from the same material as the main body 22.The lock nut 58 may be further advanced upon the connecting rod 48 tocompress the spring means to a desired degree. Preferably, the lock nut58 is advanced upon the connecting rod 48 so as to compress the washersprings 56 until increased resistance is noted. This may occur at aboveabout 75% compression, and may preferably occur at about 90%compression. A gap 62 located across the lock nut 58 may be suitablyclosed to enhance a substantially secured position of the lock nut 58upon the upper threaded portion 60 of the connecting rod 48, therebysecuring the washer springs 56 within the recess 54, and therebyproviding a supplemental biasing arrangement between the connecting rod48 and the main body 22. As such, the first bone attachment device 20 isin an enhanced compliantly attached arrangement.

The lock nut 58 is provided with retention means for enhancing thesubstantially secured relation of the lock nut 58. The retention meansis shown in the form of a retention screw 64 which is operable totraverse a correspondingly threaded receiving hole disposed across thelock nut 58 on either side of the gap 62. The retention screw 64 isoperable to be threadably tightened to close the gap 62 to the pointwhere the lock nut 58 is enhanced in a substantially secured relationagainst the upper threaded portion 60 of the connecting rod 48. Therelative positions of the lock nut 58, the washer springs 56 and therecess 54 are illustrated in FIG. 5, which is a top view illustrating aportion of the bone attachment device shown in FIG. 4, taken from theperspective 5—5 in FIG. 4. It will be appreciated that other suitablespring biasing means and retention means may be used. For example, a nutwithout a gap followed by a lock nut may be used. A lock wire disposedthrough a hole in a nut is also suitable as a locking means for thespring biasing means.

The spring biasing means may also be provided as a combination of a nutwithout a gap, followed by means for enhancing a secured relation of thenut upon the connecting rod. This may be provided as a lock nut, aspreviously described, or may be provided in another suitable form, suchas a lock wire disposed through an aperture of the nut.

Referring again to FIG. 4, the first bone attachment device 20 may alsobe provided with a porous interface coating 66 located upon theinterface surface 32. The porous interface coating 66 may be applied byany suitable technique and is for enhancing bone ingrowth into the firstbone attachment device 20 from an adjacently positioned milled endportion of a bone, such as that shown at 30 in FIG. 2. The porousinterface coating 66 may be made from varieties of the same material asthe main body 22, or may also be CoCr (cobalt chromium) beads ofdiameter approximately 20/1000ths of an inch, sintered together, or apressed and sintered multiple layer wire grid of titanium alloy wires,or a pressed and sintered coarse wire of one of the above materials, ora plasma sprayed titanium. The porous interface coating 66 may alsoinclude a hydroxyapatite layer in conjunction with any of the abovematerial layers.

With reference again to FIG. 4, the first bone attachment device 20 maybe provided with one or more antirotation pins 68 which are disposedwithin the pin channel 26 and protrude from the interface surface 32 inthe region where the main body 22 contacts an adjacently positionedmilled end portion of a bone, such as that shown at 30 in FIG. 2.Referring now to FIG. 6, which is a bottom view illustrating thecompliant section of the bone fixation device, taken from a perspective6—6 in FIG. 4, it can be seen that a plurality of antirotation pins 68are disposed in a substantially equally spaced circular arrangementabout the central axis of the longitudinal bore 28. It will beappreciated that any suitable number of antirotation pins 68 may beemployed. Usually, at least one, up to about twelve antirotation pins 68will be most practical. The preferred length of projection, above theinterface surface 32, of each antirotation pin 68 is less than fourtimes the diameter of each pin. The antirotation pins 68 may be madefrom the same material as the main body 22.

In the situation where only a mid-diaphyseal segment replacement isperformed, the second portion 14 discussed in connection with FIG. 1 mayin part take on a substantially similar construction as the firstremaining bone portion 12. Thus, a bone attachment assembly 18 may beformed from two substantially identically constructed bone attachmentdevices. Alternatively, the second portion 14 may be provided entirelyas an orthopedic appliance. Alternatively, the resection could includeadjacent portions of two end-on-end disposed long bones, such that thetwo attachment assemblies and an interposed orthopedic appliance wouldserve to restore physiologic linkage between the two long bones. In thisway, the two long bones could also be functionally fused, according tothe selected interposed orthopedic appliance.

In this situation, a second bone attachment device (not shown) may beprovided to be substantially similar to the first bone attachment device20. It may also be substantially different, for example, attached to itsreceiving surface with bone cement. With reference now to FIG. 7, FIG. 7illustrates a bone attachment assembly, indicated generally at 18. Thebone attachment assembly 18 is shown to include a first bone attachmentdevice 20 which is fixedly secured to a first remaining bone portion 12,in the manner previously described. The first bone attachment device 20may then be connected through the use of a clamp 76 to a second portion14 which is in the form of an orthopedic appliance. The orthopedicappliance may then be similarly connected to a second bone attachmentdevice in a similar manner. In this arrangement, the first boneattachment device 20 acts as a connector, in addition to the orthopedicappliance, which may replace a portion of the length of bone removedduring the surgical procedure. In this arrangement, the first boneattachment device 20 and the second bone attachment device are eachprovided with a compliant capability.

The biocompatible bone attachment assembly 18 is also shown to includemeans for enhancing a fluid seal between the intramedullary cavity 16and the external environment. Preferably, this is provided as one ormore sealing devices, such as o-rings 70 and 72, which are disposed in acontacting relation with the main body 22 or the connecting rod 48. Assuch, the o-rings 70 and 72 may be disposed about the edge of the mainbody 22, within a recess 74 created at the lower surface of the mainbody 22 adjacent to the connecting rod 48, as shown in FIG. 7, or may bedisposed upon other suitable regions of the main body 22. The o-rings 70and 72 may thus also be disposed about the lock nut 58 or the washersprings 56.

When one or more o-rings 70 and 72 are used, they may enhance a sealedcondition of the first bone attachment device 20 as connected to anorthopedic appliance, such as that shown at 14 in FIG. 1. Multiplesealing devices may sequentially reinforce a seal of the first boneattachment device 20 at the entrance to the recess 54 and the entranceto the longitudinal bore 28.

The bone attachment assembly 18 further includes means for securing thefirst bone attachment device 20 in an enhanced secured relation to thesecond portion 14 which may be an orthopedic appliance, as shown inFIGS. 1, 4 and 7. This is preferably provided as a clamp which isoperable to substantially surround a portion of the main body 22 of thefirst bone attachment device 20 and a portion of the opposing orthopedicappliance, or second portion 14. One particularly preferred type ofclamp is a cylindrically-shaped sleeve clamp 76 which is operable forbeing enhanced in a secured relation. As shown in FIGS. 5 and 6, thesleeve clamp 76 includes an aperture 78 that is operable to be closedthrough the threaded rotation of one or more retention screws 80. Thesleeve clamp 76 may be made from the same material as the main body 22.It will be appreciated that other suitable means for coupling the firstbone attachment device 20 and the second portion 14 may also be used.

The first bone attachment device 20 may also include means forpreventing rotation of the sleeve clamp 76 with respect to the main body22 and the orthopedic appliance 14. This is preferably provided as a key82 disposed in an engaging relation between the sleeve clamp 76 and themain body 22, as shown in FIG. 5. It will be appreciated that this maybe provided by any suitable device disposed between the sleeve clamp 76,the main body 22 and the orthopedic appliance 14.

Referring now to FIG. 8, FIG. 8 is a perspective view illustrating aguide device which can be temporarily applied for creating one or moreapertures in the first remaining bone portion for accepting one or moreengagement means, such as the transverse pins 44 or interlocking screws46 shown in FIGS. 2 and 3. The guide device, shown generally at 84, isoperable to be attached to a means for anchoring a bone attachmentassembly, such as the anchor body 38. The guide device 84 is made fromaluminum, a titanium alloy, or preferably, stainless steel. It will beappreciated that other suitable materials may be used. The guide device84 includes a guide body 86 that is preferably of length at least equalto the total, combined length of the connecting rod 48 and the anchorbody 38.

The guide device 84 is shown to include a guide body 86 operable forbeing disposed adjacent to the first remaining bone portion 12. Theguide body 86 includes an upper connecting aperture 88 and a lockingscrew 90 that is operable for closing the connecting aperture 88. Theguide body 86 also includes one or more guide holes 92 for guiding anaperture-forming procedure by accepting the insertion of both alignmentdevices and drilling implements, as will be discussed below.

The guide device 84 also includes a cannulated holder bar 94 that isoperable for being positioned upon the anchor body 38 and connecting rod48 within the first intramedullary cavity 16 in a coaxial relationship.The holder bar 94 is preferably positioned so as to abut against the topof the anchor body 38. The holder bar 94 is of preselected length andconfiguration to match the dimensions of the reamed first intramedullarycavity 16. As such, the length of the holder bar 94 is preferablysufficient to protrude from the osteotomy surface, yet is short enoughto allow the holder bar 94 to be substantially secured to the connectingrod 48 by a nut 96 threaded onto the connecting rod 48 substantiallyagainst the upper surface of the holder bar 94. The holder bar 94 may beof cylindrical shape, and may include a tapered section 98 disposedbetween a large section 100 having a major diameter and a small section102 having a minor diameter. The large section 100 is preferablyoperable to fit with reduced lateral movement against the walls definingthe first intramedullary cavity 16, so as to serve as a means forestablishing a precise coaxial position of the anchoring means withinthe first intramedullary cavity 16. One or more other suitable surfaceirregularities on the holder bar 94 may serve as a means forestablishing a precise depth of insertion.

The guide device 84 is also shown to include a positioning bar 104operable for being mounted between the holder bar 94 and the guide body86. The positioning bar 104 includes a connecting aperture 106 that isoperable for engaging a portion of the holder bar 94. The positioningbar 104 also includes a locking screw 108 for closing the connectingaperture 106 so as to enhance a secured relation between the holder bar94 and the positioning bar 104. The positioning bar 104 is preferablysized so as to engage the upper connecting aperture 88 of the guide body86, such that the tightening of the locking screw 90 enhances a securedrelation between the positioning bar 104 and the guide body 86. It willbe appreciated that the various components of the guide device 84described above are relatively manipulable and may thus be independentlyadjusted and set for each particular aperture-forming procedure uponeach particular first remaining bone portion 12. The guide device 84 ispreferably set to provide one or more guide holes 92 in substantialalignment with one or more apertures 40 disposed within the anchor body38, so that a drilling procedure directed through one or more guideholes 92 may result in the proper formation of the fixation bores 42shown in FIGS. 2 and 3.

As shown in FIGS. 8 and 9, the present invention also contemplates theuse of one or more self-centering drill bits 112 as especially suitablefor creating at least one fixation bore 42 by being inserted througheach of the guide holes 92 and directed toward the outer surface of thefirst remaining bone portion 12. The self-centering drill bit 112 isknown in the machine tool industry, and is shown to include a main bitportion 114 and a centering bit portion 116 protruding beyond the mainbit portion 114 for drilling a centering hole which guides the drillingoperation of the main bit portion 114. The drill bit 112 also includes adrill attachment portion 118 operable for attaching directly to adrilling device (not shown), such as a conventional hand drill. Thisprocedure may also be performed with a standard drill bit (not shown).

Referring now to FIG. 10, FIG. 10 is a partial cut away viewillustrating a milling device, shown generally at 120, for milling theosteotomy surface of a first remaining bone portion 12 in a preselectedgeometry to be coaxial with a first bone attachment device 20. Themilling device 120 is shown to include a milling body 122 having acutting edge 124 of preselected geometry. The preselected geometry ofthe cutting edge 124 may preferably be such that it creates a conicalshape, and more preferably creates a convex conical shape. The millingdevice 120 further includes means for positioning the milling body 120upon an osteotomy surface of a first remaining bone portion 12 in acoaxial relationship with the first intramedullary cavity 16. This maybe provided as a cannulated pilot member 126 that is operable for beinginserted into the first intramedullary cavity 16 up to an abuttingrelationship with the anchor body 38. Preferably, the cannulated pilotmember 126 is of a generally tapered configuration, and includes acylindrical portion 128 having a major diameter substantially equal tothe diameter of the first intramedullary cavity 16. As such, this majordiameter defines the nominal size of the cannulated stem portion 34which is subsequently inserted into the first intramedullary cavity 16.The cannulated pilot member 126 further includes a tip portion 130 whichis operable to abut against the anchor body 38. The cannulated pilotmember 126 includes a longitudinal aperture 132 that is sized to acceptthe traverse of the connecting rod 48.

The milling device 120 further includes means for positioning themilling body 122 in a coaxial relationship with the first intramedullarycavity 16. This is provided by the cylindrical portion 128 as previouslydescribed and the connecting rod 48 in the longitudinal aperture 132.The milling device 120 also includes means for establishing apreselected depth for a milling procedure upon the osteotomy surface.This is provided in the form of a preselected length of the cannulatedpilot member 126 from the cutting edge 124 to the tip portion 130. Thisdistance is preselected to be substantially equal to a desired distancefrom the anchor body 38 to the subsequently milled osteotomy surface.The cannulated pilot member 126 further includes a shaft portion 134 ofpreselected length to engage a recess 136 of preselected length withinthe milling body 122. The milling body 122 may further include a meansfor enhancing a substantially secured relation between the milling body122 and the cannulated pilot member 126, such as a set screw 138. Themilling body 122 also includes a drill attachment portion 140 forattaching the milling body 122 to a drilling device, such as aconventional hand drill.

As shown in FIG. 11, the means for positioning the milling body 122 in acoaxial relationship with the first intramedullary cavity 16, as well asthe means for establishing a preselected depth for a milling procedurecan both be provided with a different cannulated pilot member 126, andthrough a special configuration of the milling body 122 with respect tothe connecting rod 48. FIG. 11 is a cross-sectional view illustrating amilling device used for milling an osteotomy surface in a preselectedgeometry. The milling body 122 may be disposed upon the connecting rod48 such that the connecting rod 48 extends into the recess 136, andwherein the recess 136 is disposed in a coaxial relation to the firstintramedullary cavity 16, by way of the longitudinal aperture 132 in atruncated cannulated pilot member 127. In this arrangement, the meansfor establishing a preselected depth for a milling procedure is providedby the cylindrical walls defining the recess 136 being of a preselectedlength substantially equal to the length of the portion of theconnecting rod 48 which is greater than the desired distance from theanchor body 38 to the subsequently milled osteotomy surface.

Referring now to FIG. 12, FIG. 12 is a cross-sectional view illustratinga first bone attachment device 20 secured in conjunction with aninterposed orthopedic appliance 142. The orthopedic appliance 142 isshown to include a plurality of recesses 144, 146 and 148 foraccommodating the insertion of one or more of the washer springs 56, thelock nut 58 and the connecting rod 48. In this example, it should benoted that the main body 22 is shaped somewhat differently thanpreviously described in that the recess 54 may be substantially smaller,thereby allowing the protrusion of one or more of the above components.

Referring now to FIG. 13, FIG. 13 is a cross-sectional view illustratinga percutaneous bar 150 connected to a device of the present invention.The percutaneous bar 150 is secured substantially as before by acylindrically-shaped sleeve clamp 76. The percutaneous bar 150 is usedin the case of amputees, wherein the skin 152 may be repaired around thepercutaneous bar 150 during the surgical procedure. The percutaneous bar150 is shown to include as an example a threaded portion 154 which isoperable to be threadably engaged with one of several types of externalappliances (not shown). The length of the percutaneous bar 150preferably allows sufficient length of the threaded portion 154 for asatisfactory threaded engagement with the external appliance used. Thepercutaneous bar may be constructed from a material selected from thegroup consisting of metals and carbon fiber-reinforced resins, althoughit will be appreciated that other suitable materials may be used. Thepercutaneous bar 150 may further be coated with a material that allowsthe biological attachment of soft tissue, such as skin, and inhibitsbacterial access from the external environment. This is preferablyprovided as a coating 156 disposed upon at least a portion of theexternal surface of the percutaneous bar 150. Preferably, the coatingmaterial is hydroxyapatite, although it will be appreciated that othersuitable coating materials may be used.

Referring now to FIG. 14, FIG. 14 is a perspective view illustrating areaming device 158 of the present invention. The reaming device 158 isoperable for creating an enlarged cylindrical intramedullary cavity,such as the first intramedullary cavity 16, within a first remainingbone portion 12. The reaming device 158 is shown to include acylindrical portion 160 preferably having a plurality of cuttingsurfaces, and a tapered tip portion 162 disposed in communication withthe cylindrical portion 160. The tapered tip portion 162 also preferablyhas a plurality of cutting surfaces. The reaming device 158 alsoincludes a drill attachment portion, which is provided as a drillattachment post 164. The reaming device 158 is preferably a left spiral,right cutting device, made for use with standard clockwise hand drills.As such, the reaming device 158 is operable for establishing a firstintramedullary cavity 16 within the first remaining bone portion 12, isself-centering, creates a cylindrical cavity, and will not seize in thebone.

In the method of the present invention, a bone segment is replaced witha biocompatible bone attachment assembly, such as that shown at 20. Thesurgical procedure, as applied to a mid-shaft osteotomy of a femur,generally involves preparing the lateral aspect of the femur for surgerywith povidone iodine, and draping the limb for aseptic surgery. Thelateral aspect of the femur is then approached between the musclebellies of the biceps femoris and the vastus lateralis. Wound closure isof a routine nature to those skilled in the art.

The method includes the step of resecting the femur at a preselectedlocation by suitable means of sawing, thereby performing a transverseosteotomy of the femur. This procedure yields a first remaining boneportion 12. The preparation of the first remaining bone portion 12 maythen be accomplished as follows. An enlarged cylindrically-shaped firstintramedullary cavity 16 is formed within the first remaining boneportion 12 up to a diameter dictated by intramedullary cavity dimensionsand to a preselected depth. The preselected depth is preferablysufficient to allow for the insertion of a means for anchoring the firstbone attachment device 20 within the first intramedullary cavity 16 tosuch a depth that subsequent connection of a means for compliantlyattaching the main body 22 to the first remaining bone portion 12 mayprotrude from the osteotomy surface.

The enlarged first intramedullary cavity is formed by attaching thereaming device 158 to a drilling device, such as a conventionalhand-held power drill, henceforth denoted as a hand drill, at the drillattachment post 164. The reaming device 158 is then inserted into theintramedullary canal. The hand drill is then activated, and the reamingdevice 158 is advanced in a longitudinal direction into the firstremaining bone portion 12, while the reaming device 158 is being rotatedby the drilling device. This is repeated with progressively largerreamers until the reaming device 158 has clearly engaged the innerwalls. A larger reamer may be used at the outlet than at the depth ofthe intramedullary cavity. A cylindrically-shaped enlarged firstintramedullary cavity 16 as an enlargement of the natural intramedullarycanal of the first remaining bone portion 12 is thus created.

The holder bar 94 of appropriate nominal diameter is first positionedupon the connecting rod 48 in an abutting relation with the anchor body38. A nut 96 is then advanced onto the upper threaded portion 60 of theconnecting rod 48 until substantially tightened against the top surfaceof the holder bar 94. The positioning bar 104 is then engaged with theholder bar 94 in a substantially perpendicular relation such that theholder bar 94 passes through the connecting aperture 106. The guide body86 is engaged with the positioning bar 104 in a substantiallyperpendicular relation by sliding the upper connecting aperture 88 overthe positioning bar 104. The apertures 40 in the anchor body 38 are thenaligned with the guide body holes 92 in the guide body 86, by way oftemporary rods (not shown) traversing both the guide body holes and theanchor body holes. The locking screws 90 and 108 may then besubstantially tightened, thereby enhancing a secured relation betweenthe guide body 86 and the anchor body 38.

Once the above components of the guide device 84 are positioned andsecured, the holder bar 94 is inserted into the intramedullary cavity 16to the depth indicated by a gauge on the side of the holder bar (notshown).

The self-centering drill bit 112 is connected to a drilling device, suchas a hand drill at the drill attachment portion 118. The self-centeringdrill bit 112 is then inserted through a guide hole 92 in asubstantially perpendicular direction to the guide body 86 to meet theouter surface of the first remaining bone portion 12. The centering bitportion 116 is first advanced into the first remaining bone portion 12as the self-centering drill bit 112 is rotated by the drilling device.The fixation bores 42 are thus created by advancing the centering bitportion 116, followed by the main bit portion 112, through the firstremaining bone portion 12 and into the anchor body 38. Theself-centering drill bit 112 may be further advanced through the entirewidth of the first remaining bone portion 12.

Once the first fixation bore 42 is created, the self-centering drill bit112 is left in the fixation bore 42 while additional fixation bores 42are created using additional self-centering drill bits 112, toadditionally stabilize the guide device 84 for the remaining drillingprocedures. The above steps may be repeated as many times as desired tocreate several fixation bores 42.

The fixation bores 42 may be created to form contiguous straightchannels through the entire width of the first remaining bone portion 12from one external surface to the other. It will be appreciated that thefixation bores 42 may be created to a limited depth within the firstremaining bone portion 12 as well. A similar procedure may be employedto create one or more fixation bores 42 through the first remaining boneportion 12 from opposite sides of the first intramedullary cavity 16 orfrom preselected relative angles. The fixation bores 42 may thus becreated all parallel in the same direction, or may be a series ofoppositely or angularly disposed fixation bores 42 created from oppositeor adjacent external surfaces of the first remaining bone portion 12 onopposite or adjacent sides of the first intramedullary cavity 16.

Once the desired fixation bores 42 have been created, one or morefixation elements, such as transverse pins 44 or interlocking screws 46are then forcibly inserted or threadably inserted into each fixationbore 42 and into each aperture 40, so as to engage the anchor body 38and the first remaining bone portion 12. The first self-centering drillbit 112 is removed only after the first fixation element has beeninserted. The guide device 84 is then disengaged and removed.

The milling device 120 is then used to create a milled end portion 30upon the first remaining bone portion 12. Where the milling device 120includes a cannulated pilot member 126, as set forth in FIG. 10, thecannulated pilot member 126 is inserted into the recess 136 of themilling body 122, until the upper edge of the cylindrical portion 128contacts the cutting edge 124. A set screw 138 is suitably tightened toenhance a secured relation between the milling body 122 and thecannulated pilot member 126. The milling body 122 is then attached atthe drill attachment portion 140 to a drilling device, such as a handdrill. The cannulated pilot member 126 is then inserted into the firstintramedullary cavity 16 such that the milling device 122 is positionedatop the first remaining bone portion 12 with its longitudinal axis in asubstantially collinear relation with that of the first remaining boneportion 12. Pressure is then exerted in a downward axial direction asthe milling device 120 is rotated by the drilling device, therebyrotating the cutting edge 124 upon the osteotomy surface, and therebyremoving portions of the bone from this surface. The rotation iscontinued until the tip portion 130 of the cannulated pilot member 126abuts against the anchor body 38. At this point, the preselecteddimensions of the above components will have caused the rotation of thecutting edge 124 to form a milled end section 30 of a preselectedgeometry corresponding to that of the cutting edge 124, which is locatedat a preselected distance from the anchor body 38.

In the situation where a truncated cannulated pilot member 127 isemployed, as shown in FIG. 11, the milling body 122 may be connected toa drilling device, such as a hand drill, at the drill attachment portion140, as before. The milling body 122 and truncated cannulated pilotmember 127 may then be disposed upon the connecting rod 48, such thatthe connecting rod 48 extends into the recess 136 of the milling body122. Then, the milling body 122 may be rotated by the hand drill asbefore, with the milling body forced in a downward axial direction untilthe upper surface of the connecting rod 48 contacts the upper surface ofthe recess 136. At this point, the preselected dimensions of theconnecting rod 48 and the recess 136 will result in the formation of amilled end portion 30 of preselected geometry and location, as before.

In accordance with the method of the present invention, the main body 22is then positioned in an abutting relation between the interface surface32 and the milled end portion 30, such that the connecting rod 48traverses the longitudinal bore 28 of the main body 22 and protrudesinto the recess 54 of the main body 22. It will be appreciated that theconnecting rod 48 may protrude above any suitable contact surface uponthe main body 22. As shown in FIG. 2, where the main body 22 includes ancannulated stem portion 34, the cannulated stem portion 34 is insertedinto the first intramedullary cavity 16 as the main body 22 ispositioned upon the milled end portion 30. The connecting rod 48 thentraverses both the longitudinal bore 28 of the main body 22 as well asthe longitudinal bore 36 of the cannulated stem portion 34. Once themain body 22 is positioned upon the milled end portion 30, the pinchannels 26 may be used to guide a suitable drilling device for thecreation of one or more recesses in the milled end portion 30 foraccepting the antirotation pins 68. Once this drilling operation iscompleted, one or more antirotation pins 68 are disposed within one ormore pin channels 26 into the milled end portion 30, thereby preventingrotation of the main body 22 with respect to the milled end portion 30.

One or more fluid seal devices, such as o-rings 70 and 72, may then bepositioned at such locations as the recess 74 shown in FIG. 7, and alsoalong the top rim of the main body 22.

In the next step of the method of the present invention, one or moresupplemental interposed compliant devices, which are preferably one ormore washer springs 56, or one or more compressible elastic cylinders,may optionally be positioned upon the connecting rod 48 such that theyare retained within the recess 54 of the main body 22. When a pluralityof washer springs 56 are used, it is preferred that they be used in anadjacent oppositely disposed relation. A retaining means, such as a locknut 58, is advanced upon the upper threaded portion 60 of the connectingrod 48 until the lock nut 58 compresses the washer springs 56 or elasticcylinders until increased resistance is noted. This may occur at aboveabout 75% compression, and may preferably occur at about 90%compression. The lock nut 58 is then enhanced in a secured relationagainst the connecting rod 48 by tightening the retention screw 64,which closes the gap 62. Where the supplemental interposed compliantdevices are not employed, the lock nut 58 is advanced directly to thebottom of the recess 54.

In the situation where the second portion 14 is an orthopedic appliance,as shown in FIGS. 1 and 7, the sleeve clamp 76 shown in FIGS. 5 and 6 isfirst positioned upon a portion of either of the main body 22 of thefirst bone attachment device 20 or the orthopedic appliance. Thereafter,the main body 22 of the first bone attachment device 20 is brought in anend to end abutting relation with a suitable portion of the orthopedicappliance, and the sleeve clamp 76 is positioned so as to substantiallysurround the main body 22 and a section of the artificial bone portion,and the key 82 is engaged, if it is to be used. The sleeve clamp 76 isthen enhanced in a substantially secured relation by tightening theretention screws 80.

In the situation where two compliant bone fixation devices are used inconnection with a first remaining bone portion 12 and a second portion14, which is in the form of a second remaining bone portion of the sameor a different bone, the above steps for creating and positioning thefirst bone attachment device 20 upon the first remaining bone portion 12are repeated in substantially identical form for creating andpositioning a second bone attachment device (not shown) upon the secondportion 14. Alternatively, the second bone portion may be attached by ameans not in accordance with this invention. In this arrangement, thesecond bone attachment device may be attached to an interposedorthopedic appliance, which is shown at 142 in FIG. 12. A sleeve clamp76 as shown in FIGS. 5 and 6 or other connecting means is positionedupon either of the main body 22 of the first bone attachment device 20or the interposed orthopedic appliance 142. The main body 22 of thefirst bone attachment device 20 is then brought in an end to endabutting relation with the interposed orthopedic appliance 142. Thesleeve clamp 76 is then positioned so as to substantially surround aportion of both the main body 22 and the interposed orthopedic appliance142, and is tightened as before.

In the situation where it is necessary to provide for the attachment ofexternal appliances following amputation, the steps of this method areprovided with reference to FIG. 13. The components of the first boneattachment device 20 are substantially assembled, as before. Apercutaneous bar 150 is positioned in an abutting relation to the mainbody 22 and the sleeve clamp 76 is secured as before. In this procedure,the skin 152 is repaired to substantially surround the percutaneous bar150 at the end of the surgery, so that the percutaneous bar 150 isoperable to extend through the repaired skin section for subsequentconnection to an external appliance.

A second embodiment of the present invention will now be described withreference to FIGS. 15–25. Referring now to FIG. 15, there is shown anelevational view with partial breakaway illustrating the environment ofa second embodiment of the apparatus of the present invention. FIG. 15shows a bone attachment assembly 200 in an implanted condition within aremaining bone portion 202 following resection. The first remaining boneportion 202 is shown to be in the form of a resected femur, although itwill be appreciated that the present invention may be used with otherbones as well. The bone attachment assembly 200 is suitable for beingconnected to a second remaining bone portion, an orthopedic applianceconnected to a second remaining bone portion, an orthopedic applianceserving as a complete bone replacement, a percutaneous bar suitable forthe attachment of an external appliance or any other suitable device.Therefore, it will be appreciated that the apparatus of the presentinvention may be used as part of a replacement for a long bone diaphysisor may be used in another portion of any suitable bone. As before, anysecond remaining bone portion to which the bone attachment assembly 200may be connected may be a portion of the same bone as the firstremaining bone portion 202, or may be a portion of another bone.

The first remaining bone portion 202 is shown to include a firstintramedullary cavity 204. The first intramedullary cavity 204 maypreferably be a longitudinal bore that includes of at least a portion ofthe natural intramedullary cavity of the bone. Alternatively, the firstintramedullary cavity 204 may be a bore created in any suitable sectionof bone, such as within or across a proximal section of a femur. In anyarrangement, the first intramedullary cavity 204 is created within thebone to a preselected depth from a cut bone surface or the naturalexternal bone surface. This preselected depth preferably corresponds tothe expected depth of insertion of a portion of the bone attachmentassembly 200 within the bone.

In the version of the second embodiment of the present invention shownin FIG. 15, the first intramedullary cavity 204 is an enlarged naturalintramedullary cavity of the bone. The first intramedullary cavity 204thus substantially coincides in its longitudinal axis with that of thenatural intramedullary cavity of the bone. The bone attachment assembly200 may also be inserted within the natural intramedullary cavity of thebone, without further enlargement, where suitable.

The bone attachment assembly 200 is constructed of a suitablebiocompatible material, such as those previously described. It will beappreciated that all of the materials set forth in the second embodimentherein may be made from the same materials as previously described orany other suitable materials. The bone attachment assembly 200 includesa main body 206 that is substantially cylindrically-shaped, and ispreferably operable to be positioned upon a surface of the firstremaining bone portion 202. To provide means for contacting a bonesurface in a special relation, the main body 206 may include a specialconfiguration or extension, such as a shoulder portion 208. The surfaceof the first remaining bone portion 202 which contacts the boneattachment assembly 200 may be a cut bone surface, a natural externalbone surface, or a specially configured bone surface, such as milled endportion 210. Although the milled end portion 210 is shown in a convexconical geometry, it will be appreciated that any suitable geometry maybe used. The main body 206 preferably includes an interface surface 212for abutting against a surface of the first remaining bone portion 202.The interface surface 212 may be formed in any desired configurationupon the main body 206, the shoulder portion 208 where present, or both.Suitable configurations for the interface surface 212 include geometriescorresponding to geometries naturally occurring or formed upon the bonesurface, including planar, concave, convex, concave conical and convexconical. Preferred geometries for the interface surface 212 are thosethat maximize the advantages of maintaining desired contact, pressureand centering with relation to the bone surface. The concave conicalarrangement shown in FIG. 15 is a preferred geometry. It will beappreciated, however, that other suitable geometries may be used, whichmay include grooves, pins or any other features as may be desirable.

As shown in FIG. 15, the bone attachment assembly 200 further includesan extension 214 connected to the main body 206. The extension 214 isconfigured in a male tapered arrangement for connection with any of thedevices or remaining bone portions mentioned above. The extension 214may be connected to or may be integrally formed with the main body 206.It will be appreciated that the extension 214 may also include anysuitable configuration for facilitating attachment to any device or boneportion mentioned above. It will further be appreciated that the mainbody 206 and the extension 214 may replace a portion of the length ofbone being removed during the surgical procedure, by virtue of theirposition upon the milled end portion 210 of the first remaining boneportion 202. The extension 214 may include one or more configuredsurfaces for engagement of one or more devices or appliances. As shownin FIGS. 15–17, this may include one or more engagement recesses 215.

When the bone surface contacting the bone attachment assembly 200 is acut surface of a long bone diaphysis, a milled end portion 210 ispreferably created in a preselected geometry relative to the firstintramedullary cavity 204, as described previously. A speciallyconfigured bone contact surface, of any type, which may be similar tothe milled end portion 210 shown in FIG. 15, may also be prepared uponany suitable section of bone. In one preferred arrangement, shown inFIG. 15, the milled end portion 210 is formed to an axisymmetricgeometry, and most preferably to a convex conical geometry, whosecross-section has a preselected included angle of inclination relativeto the longitudinal axis in the direction of the first remaining boneportion 202. This same principle can be translated to the formation ofany bone contact surface on any section of bone, especially where it isdesirable to obtain certain advantages of contact described above. Itwill therefore be appreciated that other preselected geometries andangles may also be used. The geometry of the interface surface 212 ismost preferably constructed to substantially match the geometry of themilled end portion 210, thereby providing a substantially flushinterface between the milled end portion 210 and the interface surface212. The interface surface 212 is preferably operable for acceptingbiological bone attachment by bone ingrowth and/or ongrowth. Theinterface surface 212 may also enhance stability of the main body 206with respect to the bone. Thus, the interface surface 212 may include asuitable coating or other surface treatment, as well as ridges orundulations for this purpose.

To provide means for anchoring the bone attachment assembly 200 in asubstantially stationary position within a cavity of the first remainingbone portion 202, an anchor body 216 is provided. The anchor body 216 isdisposed at the distal end of the bone attachment assembly 200 relativeto the main body 206. The anchor body 216 is preferably sized andlocated relative to the main body 206 to be disposed within the firstintramedullary cavity 204 at its distal end when the bone attachmentassembly 200 is placed within and upon a bone. The anchor body 216includes one or more apertures 218 that are operable for accepting theinsertion of one or more fixation devices. The apertures 218 maypreferably be a plurality of staggered apertures of substantially thesame preselected diameter. One possible staggered arrangement for theapertures 218 is the arrangement shown in FIG. 15. It will beappreciated, however, that any suitable arrangement for the apertures218 may be used, including those wherein the apertures 218 are inperpendicular or other non-parallel arrangement. The apertures 218 mayalso be of any suitable number and size.

To provide a passageway for the insertion of suitable engagement devicesto engage the anchor body 216, one or more fixation bores 220 arecreated through the first remaining bone portion 202. The fixation bores220 are preferably sized and located to substantially correspond to thesize and location of the apertures 218 located within the anchor body216. As such, the fixation bores 220 may also preferably be a pluralityof staggered bores created through the first remaining bone portion 202.

The bone attachment assembly 200 also includes one or more engagementdevices that are operable to provide an engagement between the anchorbody 216 and the first remaining bone portion 202. The engagementdevices enhance a substantially secured relation of the anchor body 216within the first intramedullary cavity 204. In the embodiment shown inFIG. 15, the selection of engagement device is one or more transversepins 222 operable for being inserted through one or more fixation bores220 on at least one side of the anchor body 216, and also through one ormore apertures 218 disposed across the anchor body 216. Most preferably,a plurality of transverse pins 222 are inserted through the apertures218 and the fixation bores 220 on both sides of the anchor body 216.Although the transverse pins 222 may be disposed in a substantiallyparallel relation as shown, it will be appreciated that the transversepins 222 may be disposed in other preselected directions and at otherangles as the apertures 218 and the fixation bores 220 may be disposed.As before, it will be appreciated that the selection of engagementdevice may also be one or more interlocking screws or other suitabledevices. In addition, the engagement devices may be inserted fromopposite sides of the anchor body 216, as before.

The bone attachment assembly 200 of the present invention exhibits apreselected state of compliance that is retained in the implantedcondition of the assembly. Furthermore, the bone attachment assembly 200in an implanted condition applies a force across the milled end portion210 which maintains interface stability. The force applied by thecompliant section 224 in an expanded condition is generally in the rangeof from about 100 lbs. to about 1000 lbs. A typical amount of forceapplied is 400 lbs. Upon implantation, this force is distributed acrossthe area of the bone surface, represented by the milled end portion 210.It will be appreciated the desired amount of force exerted will varyfrom application to application, and will depend upon the size of boneinvolved and the cortical wall thickness and may depend upon otherfeatures of the bone or the patient. Preferably, this involves loadingthe bone attachment assembly 200 to a condition of expansion prior toimplantation. To provide means for allowing the bone attachment assembly200 to exhibit a condition of compliance, the bone attachment assembly200 includes a compliant section 224. The compliant section 224 isdisposed between the main body 206 and the means for anchoring the boneattachment assembly 200. The compliant section 224 is preferably anelongated bar or rod that is an integrally formed extension between themain body 206 and the anchor body 216. Alternatively, the compliantsection 224 may take on any suitable construction where the compliantsection 224 is manufactured separately from the main body 206 and theanchor body 216, and assembled or attached after the individualcomponents are manufactured, or during the surgical procedure. This mayinclude a modular system of like or differing materials, and can includea traction rod attached to the compliant section 224, where the tractionrod itself is compliant relative to the bone, such that it contributesto the compliance of the system. The compliant section 224 maypreferably be of a cylindrical shape having a diameter equal to orgreater than the anchor body 216. In this arrangement, the compliantsection 224 and the anchor body 216 fit snugly within the firstintramedullary cavity 204. The bone attachment assembly 200 ispreferably preloaded prior to implantation by expanding the compliantsection 224 alone to a preselected condition of expansion, according tothe forces desired as allowed by the elastic properties of the compliantsection 224. It will be appreciated, however, that the means forallowing the bone attachment assembly 200 to exhibit to a condition ofcompliance may take on any other suitable form. For example, the boneattachment assembly 200 may include more than one compliant section ormay include a compliant section disposed in a different configuration orat a different location upon the bone attachment assembly 200 as may bedesirable for accomplishing particulars of compliance or attachment.Also, it will be appreciated that the loading of the bone attachmentassembly 200 can be accomplished in any suitable manner prior to, duringor after implantation. The compliant section 224 is maintained in acondition of expansion following implantation by securing the anchorbody 216 at a preselected location within the first intramedullarycavity 204 during a maintained expansion of the compliant section 224while the milled end portion 210 abuts the interface surface 212.

In a state of expansion during an inserted condition within a bone, thecompliant section 224 is operable for experiencing expansion andcontraction in response to physiological expansion and contraction inthe adjacent bone. Thus, one function of the bone attachment assembly200 involves the expansion and contraction of the compliant section 224as necessary to allow the substantial transfer of physiologic loadsthrough the surrounding bone, rather than through the implanted device.The compliant section 224 is preferably formed as an elongated extensionthat is made compliant to the desired degree and with the desiredcharacteristics. Preferred configurations for accomplishing thecompliance of any compliant section 224 discussed herein includeperforation into the shape of a single or double helical spring, orsprings in the shape of an accordion, although it will be appreciatedthat any suitable perforated configuration for any compliant sectiondiscussed herein may be used. The configuration shown in FIGS. 15–17 isa single helical spring configuration. Such configurations allow thecompliant section 224 to expand and contract as a coil spring. Thenumber of turns, the inner diameter of the spring, the outer diameter ofthe spring, the size of each turn and the angle of each turn of thespring configuration in the compliant section 224 can be manipulated asdesired to achieve a specific load, a specific spring rate and aspecific deflection capacity. It will be realized that in otherarrangements, other suitable non-helical configurations or perforationsor other features may be used for the compliant section 224. The presentand other embodiments of the present invention are advantageous becausethey provide compliant fixation through an integrally formed apparatus.

An advantage of the bone attachment assembly 200 of the presentinvention involves the method by which the compliant section 224 ismade. The stock from which the bone attachment assembly 200 is made isfirst machined to a desirable shape by methods well known to thoseskilled in the art. The portion of the assembly that is in the form ofan elongated bar or rod is then perforated or cut into a configurationthat will result in a compliance in this section of the assembly. Theperforation or cutting may be accomplished by electrical dischargemachining (EDM), which involves the use of a material that conductselectricity to remove material to form desired shapes in anothermaterial by using electric spark to remove pieces of the material. Thisprocess is applied to the elongated bar or rod portion of the boneattachment assembly 200 to form perforations of a desired shape, such asa helical spring arrangement, directly therein. Typically, a brass wireof a thickness ranging from about three thousandths of an inch to aboutsixteen thousandths of an inch is used to form the desired perforations.A brass wire of about twelve thousandths of an inch is one common wireused. It will be appreciated that this process may be accomplished usingother material selections, configurations and sizes for the materialused to create the perforations.

In the method of the present invention, the perforations in theelongated bar or rod are made by contacting a cutting wire with asurface of the elongated bar or rod, or by drilling an aperture into thebar or rod into which the cutting wire may be inserted. Where thecutting wire contacts the external surface of the elongated bar or rod,a single helix is formed. Where the cutting wire is inserted into anaperture formed within the elongated bar or rod, a double helix isformed. An aperture may also be created longitudinally through theelongated bar or rod as well. Where the cutting wire contacts theexternal surface of the elongated bar or rod, the cutting isaccomplished by turning the bar or rod and feeding the wire at an anglesuitable for the desired shape of cut. Where the cutting wire isinserted into an aperture formed within the elongated bar or rod, thecutting is accomplished by turning the bar or rod and feeding the wireinto the material. The speed at which the wire is fed along the bar orrod relative to its speed of rotation determines the configuration ofthe resulting perforation, such as the pitch of a helical spring beingcreated. It will be appreciated that the selection of base material andcutting material, the angle of cutting, the inside and/or outsidediameter of the bar or rod, the length of cutting and other particularsof the cutting process may be varied to adjust the characteristics ofthe spring being created. Alternatively, other methods may be utilizedto form a spring within the elongated bar or rod portion of the boreattachment assembly 200. These include water jet cutting, blade cuttingand laser cutting, as well as other methods that those skilled in theart will appreciate.

As mentioned previously, the bone attachment assembly 200 is preferablyloaded to a condition of expansion prior to completion of the surgicalprocedure. The condition of expansion is an amount of expansionsufficient to assure adequate interface compression force between themilled end portion 210 and the interface surface 212 upon completion ofthe surgical procedure. This is accomplished by converting the compliantsection 224 to a preselected condition of expansion, before, during orafter the anchor body 216 is inserted into the first intramedullarycavity 204. To provide means for converting the compliant section 224 toa condition of expansion, the present invention provides multiplemethods. In one method, a preloading rod 250 is operable to expand thecompliant section 224 by engaging the bone attachment assembly 200 onboth sides of the compliant section 224, and forcing the two sides ofthe assembly in opposite directions. As shown in FIGS. 16 and 17, thepreloading rod 250 is sized for insertion within an elongated bore 252disposed through the extension 214, the main body 206, the compliantsection 224 and into the anchor body 216 to a depth proximal of theapertures 218. To provide means for engaging the preloading rod 250 withthe bone attachment assembly 200, the preloading rod 250 includes athreaded portion 254 that may be threaded into a threaded bore 256located at the proximal end of the bore 252. The preloading rod 250 isof a greater length than that of the bore 252 so that the portion of thepreloading rod 250 distal to the threaded portion 254 may be inserted toor almost to the complete length of the bore 252. Once this distalportion of the preloading rod 250 is inserted into the bore 252, thedistal end of the preloading rod 250 engages the distal end of the bore252. Once the preloading rod 250 contacts the distal end of the bore252, any further advancement of the preloading rod 250 will cause anexpansion of the compliant section 224. Thus, subsequent threading ofthe threaded portion 254 into the threaded bore 256 causes the distalend of the preloading rod 250 to push against the distal end of the bore252, progressively forcing the distal end of the bore 252 in a distaldirection, and causing the compliant section 224 to expand progressivelyas the threaded portion 254 is advanced into the threaded bore 256. Thepreloading rod 250 further includes means for engaging a tool, such as aknob 258 at its proximal end for facilitating advancement of thepreloading rod 250.

An additional method is where the anchor body 216 and the main body 206are in place, and a traction member extends from the compliant section224 through the main body 206 and the extension 214. A removabletraction device applies a traction force to this traction member,thereby elongating the compliant section 224 and simultaneously applyingan equal interface force across the interface surface 212. When thedesired force is achieved, a position-holding device is attached to thetraction bar, preventing it from reassuming the non-expanded conditionas traction is removed. A third method is to have an extension of acompliant section extending to or through an aperture of the main body206, the extension including a threaded portion at its proximal end. Athreaded member can be advanced upon the threaded portion of theextension against the main body 206, thereby causing the expansion ofthe compliant section 224 in a proximal direction.

FIG. 16 shows the bone attachment assembly 200 in a condition prior toinsertion of the preloading rod 250, with the compliant section 224 in anon-expanded condition. FIG. 17 shows the bone attachment assembly 200with the preloading rod 250 threaded fully into the bone attachmentassembly 200, with the compliant section 224 at an intermediate state ofexpansion. It will be appreciated that the preloading rod 250 may bethreaded into the bone attachment assembly 200 to any desired degree.Preferably, the preloading rod 250 is used in the above manner topreload the bone attachment assembly 200 by expanding the compliantsection 224 prior to implantation. The compliant section 224 willtypically be expanded prior to implantation by an amount sufficient toassure adequate interface compression force upon removal of thepreloading rod 250. Once the bone attachment assembly 200 is insertedwithin the first intramedullary cavity 204 and the anchor body 216 issecured as described above, the subsequent dethreading of the preloadingrod 250 and its withdrawal from the assembly will leave the compliantsection 224 in a substantially maintained state of expansion. Theexpanded condition of the compliant section 224 is maintained in theimplanted state by the abutment of the interface surface 212 against themilled end portion 210 in combination with the maintained stationarycondition of the anchor body 216 by the fixation devices such as thetransverse pins 222.

Referring now to FIG. 18, there is shown a bone attachment assembly 200according to the present invention in conjunction with a femoralprosthesis 270. The femoral prosthesis 270 is shown to include anaperture 272 having a female taper substantially corresponding to themale taper of the extension 214. Thus, the femoral prosthesis 270 can bepress fitted upon the bone attachment assembly 200. The femoralprosthesis 270 is typically used in reconstructive and limb salvagesurgeries. It will be appreciated that the femoral prosthesis 270 is oneof several types of devices which can be attached to the bone attachmentassembly 200. The femoral prosthesis 270 is shown to include anintercalary extension segment 274 and a femoral component 276. It willbe appreciated that any of the devices used for connecting the boneattachment assembly 200 can be made of one or more pieces or segments.The femoral prosthesis 270 is constructed of titanium alloy, although itwill be appreciated that other suitable materials may be used. Inaddition, one or more surfaces of the femoral prosthesis 270 or anyother attached device may include a coating or other surface treatmentsuch as ridges or undulations, for promoting bone ingrowth and/orongrowth, for enhancing stability, or for enhancing any othercharacteristic of the device.

Referring now to FIGS. 19 and 20, there is shown another version of thesecond embodiment of the present invention. In this version, a boneattachment assembly is shown generally at 280. The bone attachmentassembly 280 includes a main body 282 which includes a shoulder portion284. The main body 282 is further shown to include an interface surface286, which is of a concave conical geometry in similar fashion asbefore. In this version of the bone attachment assembly 280, the mainbody 282 is shaped in a tapered configuration.

The bone attachment assembly 280 is further shown to include an anchorbody 288 located at its distal end. The anchor body 288 is shown in thisarrangement to include four apertures 290 for containing suitablefixation devices for fixation of the anchor body 288 to a surroundingremaining bone portion. As can be seen in FIG. 19, the apertures 290 arelocated in a square arrangement which is different from the staggeredarrangement of five apertures discussed previously. It will therefore beappreciated that in any version of assembly discussed herein, anysuitable aperture configuration may be used.

The bone attachment assembly 280 further includes a compliant section292 which is an elongated section disposed integrally between the mainbody 282 and the anchor body 288, in similar fashion as before. The boneattachment assembly 280 further includes an extension 294 which isgenerally of a male tapered configuration, and is suitable for directattachment of a suitable orthopedic device, as before. The boneattachment assembly 280 also includes an elongated bore 296 thattraverses the extension 294, the main body 282 and the compliant section292. As before, the bore 296 is suitable for accepting the insertion ofa rod (not shown) for expanding the compliant section 292 to a conditionof expansion. The bone attachment assembly 280 also includes a threadedbore 298 disposed at the proximal end of the bore 296. The bore 296 andthe threaded bore 298 function in substantially the same way as the bore252 and threaded bore 256 previously described. In the arrangement shownin FIG. 19, the compliant section 292 is in a non-expanded condition.

Referring now to FIG. 21, the bone attachment assembly 280 shown inFIGS. 19 and 20 is shown in a preloaded condition. To provide means forloading the compliant section 292 to a condition of expansion, thepresent invention provides a preloading rod 302, having a threadedportion 304 and a knob 306 in similar fashion as before. In thisarrangement shown in FIG. 21, the compliant section 292 is shown to bein an expanded double helical configuration. This expanded configurationis the result of inserting the preloading rod 302 within the bore 296and threading the threaded portion 304 within the threaded bore 298, insimilar fashion as before.

Referring now to FIGS. 22 and 23, there is shown the bone attachmentassembly 280 described in connection with FIGS. 19–21, in an implantedcondition within a proximal femur 308. In this arrangement, a femoralhead prosthesis 310 is shown to be press fitted upon the extension 294.Referring now to FIG. 23, it can be seen that a plurality of transversepins 312 are used to maintain the anchor body 288 in a substantiallystationary position within a cavity 314 disposed within the proximalfemur 308. It will be therefore be appreciated that the bone attachmentassembly of the present invention can be used within other portions ofbone besides an intramedullary cavity.

Referring now to FIGS. 24 and 25 there is shown another version of boneassembly according to the present invention at 380. The bone assembly380 includes a main body 382, a compliant section 384 and an anchor body386, formed in a cylindrical arrangement. The anchor body 386 includesthreads 388 for engaging the walls of a cavity within a bone, such asthe first intramedullary cavity 204 or a cavity created within a bone.In the version shown in FIGS. 24 and 25, the bone assembly 380 is fittedwith a tibial tray 390 that is attached to the main body 382 via a post392 threaded into the threaded bore 394 located within the main body382. The tibial tray 390 is operable to engage a prepared tibialsurface, another tibial surface or a device attached to a tibia. Thebone assembly 380 is thus operable to be engaged within a bone cavityvia threads 388 so that any attachment, such as the tibial tray 390 mayengage the bone at another surface. It will be appreciated that a tibialtray attachment is only one of several arrangements for this version ofthe present invention.

The compliant extension 384 can be expanded to a desired condition ofexpansion after the bone assembly 380 is threaded into a bone cavity byany suitable device. One possible device utilizes the threaded bore 394to pull the main body 382 in a proximal direction using a tibialsurface, another bone surface or a device mounted upon a tibial surfaceor other bone surface as a reference. In another arrangement, shown inFIG. 25, a hexagonal headed screw 396 is recessed within the tibial tray390 and can be dethreaded with a suitable tool within a stem of thetibial tray 390. Alternatively, the compliant section 384 can beexpanded to a desired condition of expansion prior to implantation,using a preloading rod or other preloading device, as previouslydescribed. Alternatively, a traction rod can extend from the compliantsection 384 and the traction applied to the traction rod withcounterforce applied against the tibial tray 390 expands the compliantsection 384 to the desired amount. A locking member is then advanced onthe traction rod down against the tibial tray 390, preventingre-contraction of the compliant section 384. The traction is thenremoved from the traction rod, leaving residual expansion of thecompliant section 384 and a state of compression at the interfacebetween the tibial tray 390 and the bone.

Referring now to FIG. 26, there is shown another version of the secondembodiment of the present invention. In this version, the boneattachment assembly, designated as 400, is in a modular form. The boneattachment assembly 400 includes a main body 402 having a shoulderportion 404 and an interface surface 406. A porous coating 407 isdisposed upon the interface surface 406 in this version of theinvention. The porous coating 407 is preferably a titanium particleplasma spray. Alternatively, other suitable porous coating materials maybe used, including sintered cobalt beads and titanium fibermesh pads.The porous coating 407 is operable to promote bone ingrowth and/orongrowth and is operable to enhance the engagement of the main body 402with the bone interface. The porous coating 407 is shown to be formedwith a plurality of ridges 408. These ridges 408 further enhance theengagement of the main body 402 with the bone interface, and increasethe surface area for bone ingrowth and/or ongrowth. It will beappreciated that any of the versions of the device discussed herein mayinclude a porous coating of this type. An extension 409 is attached tothe main body 402, which is generally of the same configuration aspreviously described. In this version, the main body 402 includes aplurality of recesses 410 in similar fashion to the recesses 215described in connection with FIGS. 15–17. Here, however, there are eightrecesses 410 disposed about the main body 402 approximately 45° apart.

The bone attachment assembly 400 includes an anchor body 412 having aplurality of apertures 414 for securing the anchor body 412 within abone cavity. The anchor body 412 is shown here to be a separatecomponent that includes a threaded recess 416 for connection to theremainder of the assembly. The bone attachment assembly 400 includes acompliant section 418 in the form of a helical spring, in similarfashion as before. The compliant section 418 includes a threaded post420 that is operable for connection to the anchor body 412 by beingthreaded into the threaded recess 416.

In this version, the bone attachment assembly is implanted by firstinserting the anchor body 412 into the bone cavity, such as the firstintramedullary bone cavity 204 described in connection with FIG. 15. Theanchor body 412 is substantially secured in place by any of the methodsdescribed herein. The milling of the end of the bone is then performed,using the anchor body 412 to help establish an axis. The compliantsection 418 is expanded with an expansion bolt. The assembly is theninserted into the bone cavity. The main body 402 is then rotated so asto thread the threaded post 420 into the threaded recess 416. As this isdone, the engagement of the interface surface 406 with the boneinterface surface eventually occurs, and further advancement of thethreaded post 420 into the threaded recess 416 is not possible. Thisoccurs before the shoulder of the threaded post abuts against the anchorbody 412. The expansion bolt is then removed.

As shown in FIG. 26, a sizing ring 422 is operable to be disposed uponthe bone attachment assembly 400. The sizing ring 422 is operable toeffectively enlarge the diameter of at least a portion of the boneattachment assembly 400 that is inserted within a bone cavity. Thesizing ring 422 also assists in centering the bone attachment assembly400 with respect to the bone. The sizing ring 422 is therefore disposedupon the bone attachment assembly 400 in situations where at least aportion of the bone assembly 400 is smaller than at least a portion ofthe bone cavity in which it is to be disposed. The sizing ring 422 ispreferably a cylindrical tube of internal diameter that is approximatelyequal to the external diameter of the anchor body 412 and the compliantsection 418. The sizing ring 422 is operable to be slid upon the anchorbody 412 and the compliant section 418 up to the point where it contactsthe interface surface 406. Alternatively, the sizing ring 422 may bedisposed upon any suitable section of the bone attachment assembly 400.

The sizing ring 422 includes an inner surface 424 that preferablyengages snugly against the external surface of the elongated bar makingup the anchor body 412 and the compliant section 418. The sizing ring422 may preferably include a split 426 at which the sizing ring 422 maybe slightly enlarged to facilitate its positioning upon the boneattachment assembly 400. The sizing ring 422 is preferably made of atitanium alloy, such as Ti-6Al-4V, although it will be appreciated thatany suitable material may be used. It will also be appreciated that thesizing ring 422 may take on other suitable shapes and sizes as may bedesirable for assisting in centering the bone attachment assembly 400with respect to the bone, and in enlarging the effective size of thebone attachment assembly 400.

It will be appreciated that in this procedure, the order of steps may bealtered without departing from the invention. For example, in theprocedure described above in connection with FIG. 26, the proximal bonesurface may not be milled until after the insertion of the anchor body412 within the bone cavity. In addition, the anchor body 412 may besecured within the cavity by threading it directly into the cavity, insimilar manner as that described in connection with FIG. 24.

In the method of this embodiment of the present invention, a bone isprepared by cutting or other removal or shaping of bone surfaces throughmethods well known to those skilled in the art. A suitable bone cavityis prepared along the natural intramedullary canal of the bone orthrough any other region of bone through methods well known to thoseskilled in the art. One or more suitable engagement surfaces areprepared for the engagement of the components of the device discussedherein, including any special geometries, by methods well known to thoseskilled in the art. Where desired, suitable fixation bores are createdthrough the bone, also by methods well known to those skilled in theart.

The compliant section of any version of the bone attachment assemblydescribed above is converted to a preselected condition of expansion.Where it is desirable that this be done prior to implantation, means forloading the compliant section to a condition of expansion, such as thepreloading rods and other devices discussed herein, are used to expandthe compliant section. This may include expanding the compliant sectionto the degree where the apertures through an anchor body will be alignedwith fixation bores disposed within the bone or with another suitablereference. This preferably includes inserting the rod described aboveinto the bore of the bone attachment assembly and engaging the rod witha portion of the bone attachment assembly, such as threading a threadedportion of the rod into a threaded portion of the bore, therebyexpanding the compliant section to a preloaded condition. The boneattachment assembly is then implanted within a cavity within the bone.Once the preloaded bone attachment assembly has been inserted within thebone, the means for anchoring the bone attachment assembly is secured ina substantially secured relation and the rod is disengaged from the boneattachment assembly and removed. Where expansion of the compliantsection is performed following insertion within a bone cavity, theinsertion process is performed by threading or otherwise, and theexpansion of the compliant section is then performed by utilizing asuitable expansion device. The bone attachment assembly is then securedin place, with the compliant section in expansion.

It will be appreciated that several of the components described hereincan be made in an integral fashion, or may be formed as separatecomponents that can be threaded or otherwise attached. Additionally, thecompliant section in each version can be formed in differentconfigurations and having different perforations of predefinedconfigurations to achieve certain desired results in terms of load,spring rate and deflection. It will be appreciated that the principle ofcompliant fixation set forth herein can be used in conjunction with anytype of bone by varying the sizes and configurations of the componentswithout deviating from the invention. Thus, it will be appreciated thatthe present invention may be used with any large bone of the body,including a femur, tibia, bones about the elbow and ankle, a finger, atoe or at other suitable anatomical locations where an anchoring devicewith compliant fixation is desired. In addition, it should be recognizedthat this principle of compliant fixation may also be useful in otherapplications, such as in a cabling technique.

Referring now to FIGS. 27–31, there is shown a first version of a thirdembodiment of the present invention. In this embodiment, the boneattachment assembly is provided with a sleeve for inhibiting tilting ofthe compliant section of the assembly in a non-axial direction. Thissleeve is preferably an integral extension connected to the main body ofthe assembly. The bone attachment assembly also includes severaladditional variations of anchor bodies, which may be secured within aremaining bone portion in different ways. In addition, in thisembodiment, the compliant section is provided as an integral extensionupon the anchor body.

FIG. 27 is an exploded elevational view of a bone attachment assembly,generally at 500, in a modular form. The bone attachment assembly 500includes a main body 502 having a shoulder portion 504 and an interfacesurface 506, in similar manner as before. The interface surface 506 isshown to be disposed at an angle relative to the longitudinal axis ofthe main body 502. When the interface surface 506 is so angled relativeto the longitudinal axis of the assembly, the main body has the abilityto become radially constrained against a remaining bone portion uponinstallation. It will be appreciated, however, that the interfacesurface 506 may be disposed at any other suitable angle, including aright angle, relative to the longitudinal axis of the main body 502. Themain body 502 includes a cylindrically shaped sleeve 508 disposed as anintegral extension upon the lower surface of the main body 502. Thesleeve 508 includes a recess 510 of a generally cylindrical shape thatis preferably operable for containing a substantial portion, or theentire portion, of the compliant section discussed below. The insidediameter of the recess 510 is preferably slightly greater than the outerdiameter of the compliant section and anchor which it is designed tocontain, so that the main body 502 and compliant section are free tomove in an axial direction relative to one another, but aresubstantially constrained in their abilities to move or angulate innon-axial directions relative to one another. The recess 510 ispreferably only slightly greater in inside diameter than the outerdiameter of the compliant section. It is believed that reducingnon-axial deformation of the compliant section of the assembly enhancesperformance by reducing movements and tilting of the main body relativeto the remaining bone portion after implantation.

The main body 502 and the sleeve 508 are shown in FIG. 27 to be coaxial,although this need not be the case. It will therefore be appreciatedthat any bone attachment assembly set forth herein may utilize anon-coaxial configuration between the main body and sleeve. In sucharrangements, it will be appreciated that the interface surface, such as506, may be disposed at any suitable angle relative to the sleeve, suchas 508.

The main body 502 also includes an extension 512 for attachment to anysuitable device, including an artificial limb, an intercalary segment oran opposing main body of an opposing bone attachment assembly or anarticular component. The extension 512 is shown to be of a truncatedconical configuration, although it will be appreciated that any suitableconnection shape may also be used. An aperture 514 is disposed throughthe main body 502 and extension 512, opening into the recess 510 at itsfar end. A recess 516 is also provided at the near end of the extension512, opening into the aperture 514. Together, the recess 510, theaperture 514 and the recess 516 provide a specially-configuredcontinuously hollow interior designed to accept the insertion of, andinteract with, those additional portions of the assembly that allow theassembly to apply interface pre-stress and exhibit compliance in theimplanted condition. It will be appreciated that the variousconfigurations and versions of this embodiment of the present inventionwill allow this general principle to be adjusted to any configurationnecessary to accomplish this desired result. Accordingly, it will alsobe appreciated that various combinations of assembly components may beused to accomplish the compliant result in this embodiment, and thatdifferent components may be substituted throughout to achieve this end.For example, in one version discussed below, the recess 510, aperture514 and recess 516 cooperate to allow the insertion of a traction rodintegrally formed with a compliant section of the assembly. A nut orother engagement device inserted within the recess 516 operates tosecure the traction rod relative to the main body of the assembly. Itwill be appreciated that the axis of the sleeve 508 may be the same asor may differ from the axis of the extension 512.

The bone attachment assembly 500 also includes an anchor body 520. Theanchor body 520 is shown to be formed at its far end in the shape of ahemisphere for ease of insertion. It will be appreciated that othersuitable shapes which forward any advantage, including ease of insertionand other advantages, may also be used. It is believed thathemispherical and tapered configurations generally tend to be moreeasily inserted into an enlarged intramedullary cavity of a remainingbone portion. The version of anchor body shown at 520 in FIG. 27 is thetype secured within an enlarged intramedullary cavity of a remainingbone portion by cross-pinning the anchor body 520 through the cortex ofthe remaining bone portion. Apertures 522 are provided for the passageof appropriate pins or other fixation devices through the anchor body520. Although four such apertures 522 are shown in FIG. 27, disposedabout the perimeter of the hemisphere, it will be appreciated that anysuitable number and configuration of apertures 522 may also be used. Inaddition, the apertures 522 may be angled, tapered, threaded orotherwise configured as appropriate to utilize any advantage of anychosen method of fixation through the bone cortex, including screws andexpanding mechanisms.

The bone attachment assembly 500 also includes a compliant section 524.In this embodiment, the compliant section 524 is provided as an integralextension connected to the anchor body 520. This arrangement is believedto have advantages both in facilitating installation and in performance.In keeping with the modular nature of this assembly, however, it will beappreciated that the anchor body 520 may be releasably attachable to andfrom the compliant section 524, such as through the use of a cooperatingthreaded portion and recess. The compliant section 524 is preferably ofa cylindrical shape and sized for insertion within the recess 510. Thecompliant section 524 may preferably be formed as a double helicalstructure, although it will be appreciated that other configurations,including a single helical structure and other spring-type structures,perforations, indentations and other configurations may also beacceptable. Also, the compliant section 524 may consist of a solid bar,if the material and dimensions of that bar render it sufficientlyelastic such that it is more compliant than the section of bone betweenthe interface and the anchor. Determination of the most preferredconfiguration for the compliant section 524 may depend on such factorsas spring constant, degree of unwinding upon application of force(during installation loading or during subsequent operation), deflectionof helices away from the axis with axial loading, and the relativeradial positions of start and finish of the helices, or left-hand versusright-hand direction of helices, and choice of material. The compliantsection 524 may preferably be formed by electron discharge machining orwater jet cutting a cylindrical piece of material integrally formed withthe anchor body 520. Other suitable means may also be used. An aperture526 is shown to run through the compliant section 524 and the anchorbody 520, which is believed to facilitate manufacture and function ofthe compliant section 524, as well as reduce the overall weight of theassembly.

The bone attachment assembly 500 also includes means for applyingtraction to the compliant section 524, which may also be described asmeans for converting the compliant section 524 to a condition ofexpansion. A traction rod 528 is disposed integrally as an extensionfrom the near portion of the compliant section 524. Engagement of thetraction rod 528 in a suitable manner relative to the main body 502converts the compliant section 524 to a desired condition of expansionduring installation. In this version of this embodiment, the tractionrod 528 is of a generally cylindrical configuration, and of a sizesuitable for insertion within the aperture 514, and extending into therecess 516. The traction rod 528 includes a threaded portion 530 at itsnear end for engagement with a suitable engagement device, such as anut, described below. Since the traction rod communicates force to andfrom the compliant section 524, engagement of the traction rod 528relative to the main body (which engages the remaining bone portion)acts to apply traction to the compliant section 524, and converts thecompliant section 524 to a preselected condition of expansion. Theamount of traction or expansion which may be applied to the compliantsection 524 is intended to be limited to a preselected range or guidedto a specific amount by certain configurations of the assembly andinstrumentation design. As such, the compliant section 524 may beexpanded to and beyond the elastic limit but not exceeding staticultimate stress. In a condition of expansion, the compliant section 524has the ability to react elasticly to deflections in opposing axialdirections, which is believed to be the desired reaction for a compliantimplant device. It will be appreciated that the compliant section 524may be adjusted in its degree of expansion as may be desirable toachieve the desired applied interface pre-stress forces in the implantedcondition. This may be accomplished through several portions of theassembly, including the sizing of certain components and the selecteddegree of engagement between such components such as the traction rod528 and the nut described below, and through the planned milling of bonewhich defines the distance between the step (described below) locatedupon the anchor body 520 and the interface surface of the remaining boneportion.

The anchor body 520 and compliant section 524 include several designfeatures intended to facilitate working with the bone attachmentassembly 500 in installation, adjustment and alignment. A step 532 isprovided along the near surface of the compliant section 524. This step532 acts as a limit for expansion of the compliant section 524 againstthe interior end of the recess 510. A step 534 is also provided aboutthe near perimeter of the anchor body 520. The step 534 provides anengagement surface for insertion tools and the like during installationof the anchor body 520. The anchor body 520 also includes a notch 536 orother geometric irregularity that is specifically designed forengagement by an insertion and alignment tool to assure properrotational alignment of the anchor body 520 during the creation of bonyapertures used in the cross-pinning of the anchor body 520 within aremaining bone portion into which the anchor body 520 is inserted. Itwill be appreciated that other appropriate design features may beincorporated for facilitating installation, adjustment and alignment.

FIG. 28 is a top view illustrating the main body 502, including theshoulder portion 504, extension 512, aperture 514 and recess 516. Inthis figure, the shoulder portion 504 is shown to be of a generallyelliptical configuration. It will be appreciated that any other suitableconfiguration for the shoulder portion 504 may also be used, including acircular configuration. It will also be appreciated that any of thecomponents shown herein may suitably be manufactured in a non-coaxialconfiguration between the main body 502 and the sleeve 508. The sleeve508 may also be off-center relative to the shoulder portion 504,regardless of the circular, elliptical or other configuration of theshoulder portion 504. FIG. 29 is an elevational side view of the anchorbody 520, compliant section 524, and traction rod 528, shown in FIG. 27.In this side view, 90□ removed from the side view shown in FIG. 27, theconfiguration of the apertures 522 through the anchor body 520 can beseen.

FIG. 30 is a partial cross-sectional view of the bone attachmentassembly 500 in partially assembled form. In this illustration, thetraction rod 528 is shown to be inserted within the aperture 514. Thecompliant section 524 is also shown to be inserted within the recess510. Once the anchor body 520 is secured within a remaining bone portionsuch as by cross-pinning, and the end of the remaining bone portion isoptionally milled as desired, the bone attachment assembly 500 isassembled to the form shown in FIG. 30. In this form, traction can beapplied to the traction rod 528 at the threaded portion 530 in order toapply traction to the compliant section 524 and convert the compliantsection 524 to a desired condition of expansion.

FIG. 31 illustrates this version of bone attachment assembly 500 inassembled form and installed within a proximal femur, prior toconverting the compliant section 524 to a degree of expansion.Specifically, the bone attachment assembly 500 is shown to be insertedwithin a prepared cavity 538 of a remaining bone portion 540. Theprepared cavity 538 is preferably formed by reaming with a standardcylindrical reamer or any of the reamers set forth herein, although itwill be realized that any suitable method may be used. The remainingbone portion 540 may be any human or animal bone, such as a human femur.Pins 542 are inserted through the cortex of the remaining bone portion540 and through the apertures 522 in the anchor body 520. It will beappreciated, however, that screws or any other suitable engagementdevices may also be used. A nut or other engagement device (not shown)may be subsequently threaded upon or may otherwise engage the threadedportion 530 of the traction rod 528 within the recess 516, against theinterior end surface of the recess 516, as means for engaging thetraction rod 528. In this arrangement, it can be seen that the forcesapplied to the compliant section 524 in opposing directions by virtue ofthe pins 542 securing the anchor body 520 to the cortex of the remainingbone portion 540, combined with the subsequent engagement of a nut uponthe threaded portion 530 and against the interior end surface of therecess 516, will cause the compliant section 524 to be expanded andmaintained in this condition. Thus, it can be seen that the design ofthe overall recess structure of the assembly allows for thiscommunication of force to take place. The degree to which the compliantsection 524 is expanded is based on how far the nut is threaded upon thethreaded portion 530, limited by the engagement of the step 532 with theinterior end surface of the recess 510.

The bone attachment assembly 500 may preferably be made of Ti-6Al-4Valloy, 17-4 PH stainless steel, Co—Cr—Mo alloy, 316 LVM stainless steelor any other suitable material. Certain components described herein maypurposefully be made of a different material from other components whereadvantageous. Further, it will be appreciated that in any version ofthis embodiment, one or more of the various components may be altered inits size, shape and/or connectivity. Certain components of the boneattachment assembly of the present invention may be formed in a separateconnecting fashion, rather than in an integrally formed fashion. Forexample, the threaded rod 528 may be a separately-formed component,attachable by threading or otherwise to the compliant section 524. Also,the nut and threaded portion 530 may be replaced by any suitableengagement features that maintain the principle of maintaining thecompliant section 524 in a desired degree of expansion through theapplication of opposing forces from opposing ends of the assembly (suchas by securing the anchor body 522 with respect to the bone cortex andby securing the threaded rod 528 with respect to the main body 502).Additional examples of the variations possible for the bone attachmentassembly of the present invention are discussed below. It will beappreciated that as a general matter, many characteristics of thecomponents described with respect to any of the embodiments herein maybe combined, adjusted, substituted and modified to create many differentcombinations of assemblies suitable for achieving the desired compliantfixation.

FIGS. 32 and 33 disclose a second version of the third embodiment of thepresent invention. Specifically, FIG. 32 shows a bone attachmentassembly generally at 600, which includes a main body 602, as before. Inthis version, however, the main body 602 is of a somewhat differentconfiguration than the main body 502 described in FIGS. 27, 28, 30 and31. The main body 602 includes a shoulder portion 604 with an inclinedinterface surface 602 that is angled relative to the longitudinal axisof the assembly. The shoulder portion 604 is configured in this versionto have a near surface at approximately a right angle to thelongitudinal axis of the assembly. As before, the shoulder portion 604may take on any suitable shape, such as a circular shape or anelliptical shape, when viewed from above. The main body 602 alsoincludes a cylindrically shaped sleeve 608 for reducing non-axialdeformation of the compliant section discussed below when the boneattachment assembly 600 is in an assembled condition. A cylindricallyshaped recess 610 extends through the sleeve 608 as before. In thisversion, however, the recess 610 also extends through the main body 602and through a portion of the conically shaped extension 612 connected tothe upper portion of the main body 602. Thus, in this configuration, therecess 610 is able to accommodate insertion of a much longer portion ofcompliant section, if desired. As before, the extension 612 is operablefor connection to any suitable appliance.

The bone attachment assembly 600 also includes an aperture 614 that isoperable for allowing the passage of a traction rod in similar manner asbefore. A recess 616 is located within the near portion of the extension612, which opens into the aperture 614 in similar manner as before. Therecess 616 again allows the insertion of means for engaging the tractionrod in similar manner as before. In this arrangement, the recess 616also includes a threaded portion 618 for facilitating a connection toany suitable external appliance.

FIG. 32 also shows an anchor body 620 that is formed in an elongatedcylindrical configuration. The anchor body 620 includes apertures 622 ina staggered configuration for cross-pinning of the anchor body 620within a remaining bone portion. A compliant section 624 is integrallyformed with the anchor body 620 and may be formed in a single helix,double helix, or any other suitable compliant configuration, asdiscussed previously. In this arrangement, the anchor body 620 and thecompliant section 624 can be configured to have substantially similarouter diameters. Alternatively, the outer diameter of the anchor body620 may also be greater than the outer diameter of the compliant section624. A traction rod 628 is integrally formed upon the near end of thecompliant section 624, and contains a threaded portion 630 in a similarmanner as before.

This configuration of bone attachment assembly also includes certainconfigurations intended to enhance the insertion and operability of thedevice. A step 632 is provided at the near end of the compliant section624 as a stop against the near surface of the recess 610 when the boneattachment assembly 600 is in an assembled condition. Thus, the step 632acts as a means for limiting the expansion of the compliant section 624.A recess 634 is also provided to allow for the insertion of a sleeve,discussed below, surrounding the upper portion of the anchor body 620,as a buffer between the anchor body 620 and the sleeve wall defined bythe recess 610.

FIG. 33 shows the bone attachment assembly 600 in an assembled conditionand disposed within an enlarged intramedullary cavity 638 of a remainingbone portion 640. In the installed configuration shown in FIG. 33, theanchor body 620 is substantially secured within the intramedullarycavity 638 through the use of pins 642 extending through the cortices ofthe remaining bone portion 640 and through the apertures 622 in theanchor body 620. The compliant section 624 is in an expanded conditionthrough the engagement of a nut 644 upon the threaded portion 630 of thetraction rod 628 and engagement of the nut 644 against the interior basesurface of the recess 616. A sleeve 646 is disposed within the recess634 for reducing contact between the compliant section 624 and thecylindrically shaped wall defining the recess 610. The sleeve 646 may bemade of any suitable material, such as a polymer material orbioresorbable material. It may also extend over the length of thecompliant section 624. An intercalary segment 648 is also shown to bedisposed upon the extension 612. It will be appreciated that theintercalary segment may be any suitable appliance.

FIGS. 34–36 are three elevational views illustrating three sizes of athreaded anchor body which is an alternate to the cross-pinned versionsof anchor body shown at 520 and 620. The threaded anchor bodies 700, 720and 740 are each shown to be of a generally tapered configuration andinclude tapered helical cutting threads 702, 722 and 742. The threadedanchor bodies 700, 720 and 740 may also be of a generally cylindricalconfiguration. The tapered helical cutting threads 702, 722 and 742 eachinclude a plurality of notches 704, 724 and 744 which are disposedlongitudinally across the helical threads, thereby giving them a cuttingcharacter. Accordingly, the threaded anchor bodies 700, 720 and 740 areself-tapping anchor bodies that can be directly threaded into anenlarged intramedullary cavity or otherwise prepared cavity of aremaining bone portion and secured in place without the cross-pinningused in previous versions of this embodiment. Each threaded anchor bodyis shown to be integrally formed with a compliant section 706, 726 and746. In similar manner as before, however, in keeping with the modularnature of the assembly, it will be appreciated that any of the threadedanchor bodies may be releasably attached to a compliant section, such asthrough the use of a cooperating threaded insertion portion and recess.Any of the compliant sections may be formed as a single helix, a doublehelix, or other suitable configuration. Also as before, the compliantsections 706, 726 and 746 are preferably formed by electron dischargemachining or water jet cutting.

In this arrangement of threaded anchor bodies, the compliant sections706, 726 and 746 each include a threaded recess 708, 728 and 748 foraccepting a threaded screw of the type described in connection with FIG.38. Apertures 710, 730 and 750 extend through the threaded anchor bodies700, 720 and 740 as well as through the compliant sections 706, 726 and746, in similar manner as before.

This configuration of anchor body also includes certain configuredsurfaces to facilitate insertion, adjustment and securing of thethreaded anchor bodies 700, 720 and 740. A hexagonal engagement surfaceis provided on each threaded anchor body at 712, 732 and 752 to providetransmission of insertion torque. Alternatively, slots or tabs of anysuitable configuration or other means may also be used as engagementsurfaces. This surface is suitable for engagement by a correspondinglyshaped hexagonal insertion tool that can be used to rotatably thread anyof the anchor bodies into a secure position within an enlargedintramedullary cavity. Each threaded anchor body may also be providedwith a step, at 714, 734 and 754 to provide an abutment surface forengagement of a suitable insertion tool.

FIG. 37 is a bottom perspective view illustrating the geometry of thetapered helical cutting threads 702 disposed upon the threaded anchorbody 700. It will be appreciated that this configuration is applicableto any sized threaded anchor body 700, 720 or 740, and that the taperedhelical cutting threads 702 are representative of any of the taperedhelical cutting threads 702, 722 or 742. The tapered helical cuttingthreads 702 are shown to be separated by specifically shaped notches orcutting flutes 704 that are designed to provide a cutting action for thearrangement. Between any two cutting flutes, the major radius R of thethread preferably remains constant. This is shown by the radii indiciaat R₁, R₂, R₃ and R₄. A jump in radius{tilde over ( )}R occurs for thecutting threads 702 at each cutting flute 704. As such, as one follows athread from the trailing margin of a cutting flute to the leading marginof the next cutting flute, the major radius of the thread does notchange. As one crosses the cutting flute, there is a discrete increasein the thread radius. This change in thread radius need not be constant,however, among the various levels of the cutting threads 702. For aconical shaped anchor body, however, the change in thread radius{tildeover ( )}R among cutting flutes 704 would generally be constant. It willbe appreciated that this principle applies to a single, double or othermultiple cutting flute arrangement and that any suitable shape for thenotches or flutes 704 may be used.

FIG. 38 is an elevational view illustrating a threaded screw 760 that issuitable for being threadably inserted into the threaded recess 708, 728or 748 in any of the threaded anchor bodies 700, 720 or 740. Thethreaded screw 760 includes a head 762 having a recess 764 that is shownin a configuration suitable for engagement of a flat-bladed screwdriver. It will be appreciated, however, that any suitable engagementmeans may also be used, including a hexagonal internal recess (such asfor engagement of a hex key wrench) or a hexagonal external surface forengagement of a conventional-type socket wrench or similar tool. Thethreaded screw 760 also includes a threaded portion 766 at its opposingend. The threaded portion 766 is suitable for direct engagement withinthe threaded recesses 708, 728 or 748 of any of the threaded anchorbodies shown in FIGS. 34–36. An optional, preferably hemispherical,washer 768 is also provided below the head 762 for engagement within asuitable recess that is formed as part of a main body, extension portionor other suitable attachment forming part of the bone attachmentassembly of the present invention. The washer 768 may be threaded uponthe threaded screw 760.

FIG. 39 is a partial cross-sectional view illustrating a third versionof the third embodiment of the present invention. In this version, athreaded anchor body of the type shown in FIG. 35 is used in combinationwith a main body of the type shown in FIG. 27, with a threaded screw ofthe type shown in FIG. 38 included as a means for applying traction tothe compliant section or means for expanding the compliant section to apreselected degree of expansion.

A bone attachment assembly is provided generally at 800 and includes amain body 802. The main body 802 includes a shoulder portion 804 havingan interface surface 806, in similar manner as before. A sleeve 808 isdisposed upon the main body 802, and includes a recess 810. An extension812, of a generally conical configuration, is disposed upon the near endof the main body 802. An aperture 814 is disposed within the main body802, which opens into the recess 810. A recess 816 is provided at thenear end of the extension 812, which opens into the aperture 814, suchthat the recess 816, the aperture 814, and the recess 810 provide apassageway for insertion of a threaded screw 860.

A threaded anchor body 820 is shown to be inserted within an enlargedintramedullary cavity 838 of a remaining bone portion 840. The threadedanchor body includes tapered helical cutting threads 822 having notches824, in similar manner as before. The bone attachment assembly 800 alsoincludes a compliant section 826, integrally formed with the near end ofthe threaded anchor body 820. A threaded recess 828 is provided at thenear end of the compliant section 826 so that means for engaging thecompliant section with respect to the main body, in the form of athreaded screw 860, may be threadably inserted. An aperture 830 isdisposed through the compliant section 826 and the threaded anchor body820, also as before. Engagement surfaces 832, of different geometry thanthe hexagonal engagement surface previously described, and step 834 arealso provided for engagement of this section of the bone attachmentassembly 800 by a suitable tool.

Means for engaging the compliant section 826 with the main body 802 isprovided in the form of a threaded screw 860 that is inserted throughthe aperture 814 and is threaded by its threaded portion 866 into thethreaded recess 828. The threaded screw 860 may preferably be of thetype shown at 760 in connection with FIG. 39. As the threaded screw 860is advanced into the threaded recess 828, engagement of the head 862against the interior end surface of the recess 816 causes expansion ofthe compliant section 826, since the threaded anchor body 820 isretained in place within the remaining bone portion by the taperedhelical cutting threads 822. A recess 864 is provided upon the head 862to facilitate tightening of the threaded screw 860, as previouslydescribed. It will be appreciated that the threaded screw 760 shown inFIG. 39 may also be used in conjunction with a recess, such as thatshown at 828 in FIG. 40, as a means for expansion of the compliantsection in any other embodiment described herein, such as in FIGS. 27and 29–31.

FIG. 40 illustrates a fourth version of the third embodiment of thepresent invention, wherein a standard tibial tray is used as analternative attachment for any of the main bodies previously described.The tibial tray 870 includes a recess 872 that is operable for acceptingthe insertion of a threaded screw 874, which may be a modified versionof the screw 760 shown in FIG. 38. Of course, it will be appreciatedthat the length of the screw 862 may be adjusted to suit the particularneed. The screw 862 may even be of excessive length so as to projectinto the compliant section and even into the anchor body 820. The tibialtray 870 is shown to be attached to an integral anchor body 820 andcompliant section 826 from the discussion accompanying FIG. 39, althoughit will be appreciated that any form of anchor body and compliantsection, integrally formed or not, may also be used. In addition, thecompliant section 826 may also be attached directly to the tibial tray870.

The method of using this embodiment of the present invention isdiscussed with reference to FIGS. 41–47. It will be appreciated,however, that in similar manner as before, different combinations ofmethod steps are intended to be capable of substitution for use with anyof the assembly embodiments described herein. In this embodiment of themethod of the present invention, an intramedullary cavity or othercavity of a remaining bone portion is suitably prepared for containingany of the anchor bodies described herein. In the case of thecross-secured version of anchor body 520 or 620 described in connectionwith FIGS. 27–33, a standard cylindrical reamer (not shown) well knownto those skilled in the art may be used. In those arrangements, however,where one of the threaded anchor bodies 700, 720 or 740 illustrated inFIGS. 34–36 are used, specially-shaped reamers shown in FIGS. 41–43 arepreferably used. These reamers may also be used as an alternative withthe cross-secured version of anchor body 520 or 620. Three reamers ofdifferent sizes are shown in FIGS. 41–43 at 900, 910 and 920. Eachreamer includes a shaft 902, 912 and 922 having graduated scale markings904, 914 and 924 for identifying depth of insertion of the reamer. Theshaft 902, 912 or 922 may be attached to any power drill or othersuitable powered instrument, or may alternatively be powered by hand. Acutting end 906, 916 and 926 located at the far end of each reamerincludes specially-shaped cutting surfaces 908, 918 and 928 that aredesigned to form a portion of an intramedullary cavity of a remainingbone portion to compliment the shapes of the threaded anchor bodiesshown in FIGS. 34–36. The cutting surface 928 is shown to have a maximumdiameter d representing the maximum diameter to which a cavity will bereamed using the instrument. Preferably, the diameter d is greater thanor equal to the maximum thread diameter of the anchor body to beinserted within the aperture being reamed. This principle applies forall reamer sizes.

FIG. 44 shows a suitable method for preparing an intramedullary cavity938 of a remaining bone portion 940, for insertion of a threaded anchorbody of the type shown in FIGS. 34–36. In the steps of this method ofthe present invention, the bone within which the bone attachmentassembly of the present invention is to be inserted is first cut asdesired. Cutting of the bone may involve the removal of diseased ordefective bone portions, as appropriate. The bone is cut through methodswell known to those skilled in the art, preferably at a 90□ anglerelative to the longitudinal axis of the bone. It will be appreciated,however, that this angle of cutting may also be adjusted for severalfactors, including but not limited to the configuration of the naturalintramedullary cavity of the bone, certain adjustments in theconfiguration of the main body, anchor body or compliant section of thebone attachment assembly (including non-coaxial configurations), or forother considerations. The remaining bone portion 940 may be a tibia orany other suitable bone portion. The resulting bone abutment surface 950may optionally be subsequently milled through any suitable methoddiscussed herein or other methods known to those skilled in the art.

The surgeon determines the desired width and depth for enlargement ofthe natural intramedullary cavity of the remaining bone portion 940 byfirst determining the size and configuration of the components of thebone attachment assembly to be used. This is accomplished throughselecting, from those different trial sizes available, the appropriatelysized and configured main body, tibial tray or other assembly component.Once the surgeon determines the amount of space to be taken by thechosen assembly component, a trial base plate 952 is selected forperforming a reaming operation upon the natural intramedullary cavity ofthe remaining bone portion 940. The trial base plate 952 is chosen to beof a size and configuration that will correspond to the selectedattachment to be placed upon the bone abutment surface 950 when the boneattachment assembly as a whole is installed. The trial base plate 952 istemporarily pinned into a substantially stationary position for thereaming and plug insertion process, preferably with several ⅛″ pins thatpass through the trial base plate 952 and into the bone, through methodswell known to those skilled in the art. The trial base plate 952includes a notched aperture 954. A centering disc 956, of asubstantially circular configuration, includes a notched perimetersurface 958 that is intended to substantially correspond to the notchedaperture 954 of the trial base plate 952. In this arrangement, insertionof the centering disc 956 within the notched aperture 954 of the trialbase plate 952 provides a removable and replaceable means for guiding areaming operation. The centering disc 956 includes an angled aperture960 that is of a generally conical configuration and is offset from avertical configuration by an angle □ relative to the longitudinal axisof the natural intramedullary cavity of the remaining bone portion 940.A possible selection for the value of the angle □ is 5□, although itwill be appreciated that other suitable angle values may be used. Theminimum internal diameter for the centering disc 956 is located at itsfar end, as the angled aperture 960 is angled away from the longitudinalaxis in the near direction. The angled aperture 960 is configured inthis way to allow for some freedom of angular movement during a reamingoperation, while keeping the location of intersection between the reamerlongitudinal axis and the trial base plate substantially unchanged. Assuch, the minimum internal diameter for the angled aperture 960 islocated upon the far surface of the centering disc 956, or at thepreferred level of said intersection. It will be appreciated thatdifferent diameters for the angled aperture 960 may be substituted bymerely substituting differently sized centering discs 956. Thus, in thisarrangement, a variety of freedom of movement ranges may be achievedthrough the use of differently sized centering discs 956.

In the reaming operation shown in FIG. 44, multiple graduated sizedreamers, such as the ones shown in FIGS. 41–43, are used in aprogressive manner to enlarge the natural intramedullary cavity of theremaining bone portion 940, until the cortical bone is reached that issuitable for securing an anchor body of the types used in the presentinvention. The reamers are used, preferably from smallest to largestdesired size, by placing the desired centering disc 956 upon the shaftof the particular reamer selected, and then reaming either using apowered device or by hand. In the illustration shown in FIG. 44, anintermediate-sized reamer 911 is used as a variation of theconfiguration shown for the intermediate reamer 910. This reamer 911 hasa cylindrical portion 917 corresponding to the design of the anchor bodybeing used. The reamer 911 is shown to have a centering disc 956 placedupon its shaft 912 and positioned upon the notched aperture 954 of thetrial base plate 952. Powering of the reamer 911 either by hand or withpower assisted equipment results in the formation of an enlargedintramedullary cavity, designated by the numeral 938 in FIG. 44. Thisoperation is repeated through a progressively larger series of reamersuntil the desired size for the enlarged intramedullary cavity 938 isachieved. The graduated scale markings 915 are used to identify thedesired insertion depth I for the reamer 911.

FIG. 45 illustrates the installation of a threaded anchor body of thetype shown in connection with FIGS. 34–36. For purposes of illustration,the anchor body 720 from FIG. 35 is shown in the FIG. 45 illustration.In this step of the method of the present invention, once the naturalintramedullary cavity of the remaining bone portion 940 has beensufficiently enlarged, a threaded anchor body, such as that shown at720, is inserted into the enlarged intramedullary cavity 938. With atrial base plate 952 in place upon the bone abutment surface 950, asuitably sized centering disc 956 is placed upon the cannulated shaft972 of an anchor inserter 970.

The anchor inserter 970 is a device used for securing the threadedanchor body 720 in place within the enlarged intramedullary cavity 938by rotatably threading it into place so that the tapered helical cuttingthreads 722 become secured within the cortex of the bone at the desireddistance from the bone abutment surface 950. The cannulated shaft 972 ofthe anchor inserter 970 includes an aperture 974 that is specially,sized to a small diameter over the near portion of the cannulated shaft972, while being sized to a larger diameter over the far portion of thecannulated shaft 972. The purpose for this configuration of the aperture974 is to allow the cannulated shaft 972 to be inserted over thecompliant section 726 of the threaded anchor body 720. A hexagonalrecess 976 located at the far end of the aperture 974 is sized andconfigured to engage the hexagonal engagement surface 732 of thethreaded anchor body 720. Rotation of the cannulated shaft 972 thenaccomplishes a rotating insertion of the threaded anchor body 720 withinthe enlarged intramedullary cavity 938. Graduated scale markings 978 maypreferably be disposed upon the cannulated shaft 972 for determining thedesired insertion depth I of the threaded anchor body 720 by thisdevice. A handle 980 is provided as part of the anchor inserter 970 toassist in rotation of the cannulated shaft 972 by hand. Alternatively,it will be appreciated that other configurations may also be used toassist in this insertion.

A positioning rod 982 is also provided for helping to maintain thedesired positioning and attitude of the threaded anchor body 720 duringthe insertion procedure. The positioning rod 982 can also be used forextraction. The positioning rod 982 includes a shaft 984 having athreaded portion 986 at its far end. In the operation of this device,the positioning rod 982 is engaged with the threaded recess 728 of thethreaded anchor body 720 through the threaded portion 986. A knob 990 orother torque applying means is provided at the near end of the shaft 984to facilitate gripping by hand. Preferably, the positioning rod 982 isthreadably engaged to the threaded recess 728 so that the threadedanchor body 720 may be held in place during the rotation of the anchorinserter 970 that causes fixation of the threaded anchor body 720.

In the use of the centering disc 956 in this step of the method of thepresent invention, the centering disc 956 may or may not be the samesize of centering disc 956 used in connection with FIG. 44. As can beseen in FIG. 45, the centering disc 956 has an angled aperture 960displaced in similar manner as before at an angle φ relative to thelongitudinal axis of the remaining bone portion. The angle of offsetrepresented by φ may or may not be the same as the angle □ described inconnection with FIG. 44 in the use of the reamer 911.

The depth of insertion I for the threaded anchor body 720 is determinedfrom a reading of the graduated scale markings 915 along the shaft 913of the reamer 911 during the reaming operation. The threaded anchor body720 is then advanced in an amount corresponding to the depth I readoriginally from the reamer 911 during the reaming exercise and matchingthe depth markings 978 along the shaft 972 of the anchor inserter 970.Alternatively, it may be advanced a preselected number of turns aftercortical engagement is noted. The threads 722 cut into the bone surfaceadjacent the enlarged intramedullary cavity 938 to a certain distancebeyond the reamed distance, typically about 1 or 2 mm. The surgeon alsonotes the depth of the threaded anchor body 720 to determine the lengthof screw to apply to the compliant section 726 for expanding thecompliant section 726 to the desired degree. The trial base plate 952and centering disc 956 are then removed.

Referring again to FIG. 39, in the next step of the method of thepresent invention, the desired assembly component, such as the main body802, a tibial tray such as that shown at 870 in FIG. 40, or othersuitable assembly component is then placed upon the remaining boneportion 840. In the case where a tibial tray such as that shown at 870in FIG. 40 is used, the tibial tray 870 is merely placed onto the end ofthe remaining bone portion above the compliant section 826. In thesituation where a main body is used such as in FIG. 39, the main body802 is positioned upon the remaining bone portion 840 such that thesleeve 808 is inserted within the enlarged intramedullary cavity 838over the compliant section 826. A screw, such as that shown at 864 inFIG. 39, is then inserted through the aperture 814 so that the threadedportion 866 may be threadably inserted into the threaded recess 828. Thethreaded screw 860 is then advanced by a sufficient number of turns toexpand the compliant section 826 to the desired amount.

FIG. 46 demonstrates the method of the present invention used forcross-securing, such as by cross-pinning, an anchor body of the typesshown in connection with FIGS. 27–33, within an intramedullary cavity orother prepared cavity. In FIG. 46, however, this is illustrated as onepossible variation in the configuration of the anchor body 520.Specifically, the anchor body 520 is provided with a chamfered flange550 that both facilitates component assembly and provides limitedcontact area between the anchor body 520 and the anchor holder 1002, andallows small variations in the angle between the anchor body 520 andsleeve. Accordingly, the chamfered flange 550 will also provide limitedcontact area between the anchor body 520 and any sleeve disposed as anextension of any main body. It is believed that such freedom of angle isadvantageous toward function of the assembly as a whole.

Discussion of the present method of the invention describes the stepsused for creating apertures within the surrounding bone cortex, in analigned relationship with the apertures 522 of the anchor body 520. Itwill be appreciated that similar steps may be undertaken to install theanchor body 620. The apertures created through the bone cortex are usedto secure the anchor body 520 in a substantially secured relation bycross-securing, such as through cross-pinning, cross-screwing or thelike. FIG. 46 shows an anchor body 520 with integral compliant sectionand integral traction rod 528 in relation to an enlarged intramedullarycavity 1038 of a remaining bone portion 1040. Once the components of theassembly have been inserted within the enlarged intramedullary cavity1038, a preferably adjustable drill guide, designated generally at 1000,is used to prepare apertures within the bone cortex as described above.The drill guide 1000 includes an anchor holder 1002, a cross-bar 1004and an adjustable drill jig 1006. The anchor holder 1002 includes arecess 1008 that is of a generally similar configuration to the sleeve508 of the main body 502 previously described. As such, the anchorholder 1002 does serve the function of setting the depth andestablishing the axis of the anchor holder 1002 for accomplishing thecross-drilling function. A tab 1010 is provided at the far end of theanchor holder 1002, for engaging the notch 536 in the anchor body 520.The cross-bar 1004 and the drill jig 1006 can be aligned by the surgeonsuch that the apertures 1014 in the drill jig 1006 are in the properlocation for guiding a drilling procedure within the bone cortex. A nut1051 or other suitable engagement device is tightened upon the tractionrod 528 to secure the anchor holder 1002 relative to the anchor body520. A knob 1053 is used to tighten the drill jig 1006 in an alignedposition relative to the anchor body 520. Rods (not shown) may beinserted through the apertures 1014 to facilitate and test the alignmentof the jig 1006 both prior to drilling and following the drilling of anyaperture in the bone cortex. Once the drill guide 1000 is aligned andtightened by the surgeon and inserted into the bone, a power drillingdevice of the type well-known to those skilled in the art is theninserted through the apertures 1014 and drilling is undertaken throughthe bone cortex of the remaining bone portion 1040, through theapertures 522 of the anchor body 520 and through the opposing side ofthe bone cortex. This operation is performed for all apertures 522 ofthe anchor body 520. When drilling is complete, pins are insertedthrough the apertures 1014 of the drill jig 1006. The pin length isselected by a measurement process. After the pins are placed, the nut1051 or other engagement device is removed and the drill guide 1000,including the anchor holder 1002, is removed.

Once the anchor body 520 has been secured within the remaining boneportion 1040, a main body, tibial tray or other suitable attachment isplaced upon the anchor body 520 and the compliant section 524, insimilar manner as before. Once the above components are in place, asuitable engagement device such as a nut similar to that at 1051 usedfor securing the anchor holder 1002 during the drilling procedure, isapplied to the threaded portion 530 of the traction rod 528. The nut istightened a sufficient number of turns as determined by the surgeon forexpanding the compliant section 524 to the desired degree.

FIG. 47 shows a tool for use in the optional milling of a bone abutmentsurface. More specifically, FIG. 47 shows a pilot member 1060 that fitsover the compliant section 524 of the bone attachment assembly, insimilar manner as before. The pilot member includes a recess 1062 sothat the pilot member 1060 can be inserted over the compliant section524 until it meets the step 534 forming a portion of the near surface ofthe anchor body 520. The anchor body 520 is also shown to include adifferent configuration, in the form of a spherically-shaped contactregion 552 of radius r, that facilitates component assembly and providesa small angular freedom between it and any sleeve attached to any mainbody, in a different way than the chamfered flange 550 shown in FIG. 46.The pilot member 1060 includes a shaft 1064 designed to be fitted overthe traction rod 528 integrally formed with the compliant section 524.

A milling device 1070 is shown to include a cutting end 1072 at apredetermined angle relative to the longitudinal axis of the remainingbone portion 1040 to be milled. This angle can be perpendicular to thelongitudinal axis or at any suitable angle. The milling device 1070 alsoincludes a recess 1074 shaped to fit over the shaft 1064 of the pilotmember 1060. A shaft 1076 is also provided for attachment to a powerdrill or any other powered attachment suitable for rotating the millingdevice 1070 at a high speed. A set screw 1078 is also provided fortightening the milling device 1070 against the shaft 1064.

In operation, rotation of the milling device 1070 against an abutmentsurface 1050 of a remaining bone portion 1040 causes the cutting end1072 to mill the abutment surface 1050 into a shape represented by thecutting end 1072. As shown in FIG. 47, operation of the milling device1070 shapes the abutment surface 1050 to an angle in a directioncorresponding to the angle represented by the cutting end 1072.Following this procedure, the milling device 1070 and pilot member 1060are removed, and the remaining steps of the procedure for securing thebone attachment assembly components and for expanding the compliantsection are followed in similar manner as previously described.

Yet another embodiment of the bone attachment assembly of the presentinvention is described in connection with FIGS. 48–51. Specifically,FIG. 48 shows one version of this embodiment of bone attachment assemblygenerally at 1100. The bone attachment assembly 1100 includes a mainbody 1102 having an articular portion 1104. In this configuration, thearticular portion 1104 is of a generally convex cross-section so as tohave a complimentary shaped interface surface 1106. As such, theinterface surface 1106 is suitable for being applied directly upon asurface of a remaining bone portion, such as a proximal femur, that hasbeen shaped through milling or other available methods to a generallyconvex configuration.

The bone attachment assembly 1100 also includes an anchor body 1120having apertures 1122 for securing the anchor body 1120 by cross-pinningor cross-screwing in a similar manner as before. The anchor body 1120also includes a compliant section 1124. An aperture 1126 is also shownto pass through the anchor body 1120 and compliant section 1124, in asimilar manner as before. In this arrangement, the anchor body 1120, thecompliant section 1124 and the main body 1102 are shown to be integrallyformed. A threaded recess 1128 is provided at the far end of theaperture 1126 for threaded engagement of an expansion rod 1130, which isinserted from the far end into the aperture 1126, threaded with itsthreaded portion 1132 into an engagement with the threaded recess 1128,and removed from the far end of the assembly once the anchor body 1120is secured in place. A knob 1134 may preferably be provided forfacilitating insertion of the expansion rod 1130 and engagement with thethreaded recess 1128. It will be appreciated that the knob 1134 may takeon any suitable shape, such as a hexagonal shape, and may include asuitable means, such as a slot or recess, for engagement by a suitabletool, such as a screwdriver or a hex key wrench. FIG. 48 shows the knob1134 to be provided with a hexagonal recess 1136, that is engaged by atorsion applying instrument such as hexagonal shaft 1138.

Alternatively, it will be appreciated that the expansion rod 1130 mayalso take the form of a long shaft having a threaded portion atmid-section, effectively combining the knob 1134 and hexagonal shaft1138. In a similar manner as before, insertion of the expansion rod 1130within the aperture 1126 and subsequent threading of the threadedportion 1132 with the threaded recess 1128 operates to expand thecompliant section 1124 to a preselected condition of expansion. Sincethe expansion rod 1130, as well as the expansion rods shown inconnection with FIGS. 49–51, expand each of the respective compliantsections from beneath, they must each be removed from beneath followingthe cross-pinning or other securing of the respective anchor bodies.This can be accomplished by a removal of the expansion rod through acontinuation of the aperture into which the assembly is inserted,through a smaller diameter extension of this aperture or through acomplimentary aperture formed from the end of the remaining bone portionopposite the main body.

FIG. 51 illustrates the installation of the version of bone attachmentassembly shown in FIG. 48 within a human femur. The femoral head isfirst prepared to a spherical, cylindrical or conical configurationthrough methods well known to those skilled in the art. The configuredfemoral head may also include chamfered ends adjacent the spherical,cylindrical or conical configuration. A cavity 1150 is then reamed alongthe axis of the femoral neck by any of the methods described herein. Anaperture 1151 is prepared through reaming, drilling or otherwise as anextension of the cavity 1150 passing through the cortex opposing themain body 1102. The aperture 1151 may be created from either cortexalong the longitudinal axis of the cavity 1150. The aperture maypreferably be of smaller diameter than the cavity 1150, and ispreferably created after the cavity 1150 is created. Alternatively, thecavity 1150 may be prepared to extend entirely through the femur 1152.

An expansion rod is provided in FIG. 51 in an extended length form at1160, with a centrally-located threaded portion 1162 for engaging thethreaded recess 1128. The expansion rod 1160 may also preferably includean engagement configuration such as a hexagonally-shaped end 1164 forengagement by a wrench or other tool. The expansion rod 1160 is insertedinto the aperture 1126 and threaded into the threaded recess 1128 toexpand the compliant section 1 124 to its intended force. The componentsof the bone attachment assembly 1100, including the anchor body 1120,the compliant section 1124 and main body 1102, including the articularportion 1104, are then inserted within the cavity 1150 and applied uponthe prepared exterior surface of the femur. The expansion rod 1160extends through the aperture 1151 and through the cortex proximate theanchor 1120. The aperture 1151 allows for any adjustment of expansion ofthe compliant section 1124 to be made. In the case where an extensionrod of the type shown at 1130 in FIG. 48 is used, it can also bemanipulated through the aperture 1151.

While the main body 1102, including the shoulder portion 1104, is heldagainst the prepared femur surface, the anchor body 1120 is secured inplace within the femur 1152 such as through the use of pins 1158, usingsimilar method steps involving cross-drilling of apertures through thebone cortices and anchor body apertures 1122 and subsequent insertion ofpins as previously described. Screws or other suitable fixation devicesmay also be used. Once the anchor body 1120 has been secured within thefemur 1152, the expansion rod 1160 is removed from within the aperture1126, through the aperture 1151 so as to allow the compliant section1124 to exert force directly on the bony surfaces contacting thecross-pins and the main body 1102. Alternatively, it will be appreciatedthat a threaded traction rod may be integrally formed with the compliantsection 1124 and expanded using a nut arrangement, in similar manner asbefore.

Another version of this embodiment of the present invention is shown inFIG. 49. Specifically, FIG. 49 illustrates a two-piece bone attachmentassembly generally at 1200. The bone attachment assembly 1200 includes amain body 1202 having an articular portion 1204 which includes aninterface surface 1206 in substantially the same shape as that describedin connection with FIG. 48. In this arrangement, however, the main body1202 contains a threaded recess 1208 for allowing assembly of thecomponents of the bone attachment assembly 1200 during the surgicalprocedure.

The bone attachment assembly 1200 includes an anchor body 1220 havingapertures 1222 suitable for cross-pinning, cross-screwing or the like.An integrally formed compliant section 1224 is also provided in asimilar manner as before, and an aperture 1226 extends through theanchor body 1220 and the compliant section 1224, also in a similarmanner as before. A connecting rod 1228 is provided at the near end ofthe compliant section 1224, and includes a threaded portion 1230 forengaging the threaded recess 1208 of the main body 1202. In a similarmanner as before, the compliant section 1224 is expanded through theinsertion of an expansion rod 1234 within the aperture 1226 and engagingthe threaded portion 1236 of the expansion rod 1234 with a threadedrecess 1232 located at the far end of the aperture 1226.

In the method involving this two-piece embodiment of the bone attachmentassembly 1200, the femoral head is prepared substantially as before. Acavity and aperture are also prepared within the femur as before alongthe axis of the femoral neck. The expansion rod 1234 is inserted withinthe aperture 1226 and is threaded into the threaded recess 1232, therebypre-expanding the compliant section 1224. The components are theninserted and placed upon to the remaining bone portion in similar manneras before. After the anchor body 1220 is affixed to the surrounding bonecortices with cross-pins or the like using the drill guide as before,the main body 1202 is then threaded onto the connecting rod 1228 snuglyagainst the bone interface, and then the expansion rod 1234 is removedthrough the end of the bone aperture proximate the anchor 1220 so as toallow the compliant section 1224 to exert force directly on the bonysurfaces contacting the cross-pins and the main body 1202.Alternatively, in this two-piece arrangement, the main body 1202 can bethreadably attached to the compliant section 1224 before thecross-pinning has occurred and before the expansion rod is removed.

FIG. 50 illustrates yet another version of this embodiment of thepresent invention, wherein a bone attachment assembly is providedgenerally at 1300. The bone attachment assembly 1300 includes a mainbody 1302 having an articular portion 1304 with an interface surface1306 in similar configuration as before. In this arrangement, however, acylindrically shaped sleeve 1308 is provided as an extension upon themain body 1302 in a similar manner as in previous embodiments. Thesleeve 1308 is shown to include a recess 1310 with a threaded aperture1312 at its near end. This arrangement also allows for separate assemblyof these components during the surgical procedure.

The bone attachment assembly 1300 also includes an anchor body 1320,which is of a similar shape as the anchor body 520 shown in FIG. 31. Theanchor body 1320 includes apertures 1322 and includes a step 1332 forengaging a suitable installation tool, and for acting as a stop againstthe far surface of the sleeve 1308 that regulates the amount ofexpansion for the compliant section 1324. The compliant section 1324 isintegrally formed with the anchor body 1320 and an aperture 1326 extendsthrough the anchor body 1320 and the compliant section 1324 in a similarmanner as before. A connection rod 1328 is provided as an integralextension from the near end of the compliant section 1324. Theconnection rod 1328 includes a threaded portion 1330 suitable forengaging the threaded aperture 1312. The installation of this version ofbone attachment assembly 1300 involves insertion of the compliantsection 1324 into the recess 1310 and threading the threaded portion1330 into the threaded aperture 1312. An expansion rod (not shown)having a threaded portion is used in similar manner as before forengaging a threaded recess 1338 located at the far end of the aperture1326. Threading such an expansion rod into the aperture 1326 causesexpansion of the compliant section 1324 in similar manner as before. Insimilar manner as before, the expansion rod is removed from within theaperture 1326 following installation and cross-pinning and applicationof the main body 1302, to activate the compliant force directly onto thebony surfaces adjacent the main body 1302 and the cross-pins.

Yet another version of this embodiment of the present invention is shownin connection with FIG. 52. In this version, a bone attachment assemblyis provided at 1400 in a non-coaxial configuration. The bone attachmentassembly 1400 includes a main body 1402 having a shoulder portion 1404and an interface surface 1406 with a bone ingrowth enhancing texture. Asleeve 1408 extends from the main body 1402 in similar manner as before.An anchor body 1410 and compliant section 1412 are integrally formed,with a threaded recess 1414 disposed at the near end of the compliantsection 1412. A traction rod 1416 is also provided for expanding thecompliant section 1412 relative to the main body 1402. In thisarrangement, however, an extension 1418 is provided upon the main body1402 in a non-coaxial relationship relative to the sleeve 1408. Thetraction rod 1416 is suitable for being inserted through the main body1402 to the side of the extension 1418. This version is intended todemonstrate the ability of any component of the invention to be alteredin its axial configuration relative to other components to achieve anyadvantage. In this arrangement, the non-coaxial configuration of theextension 1418 allows increased freedom of sleeve placement within thebone, thereby allowing positioning of a femoral head, for example,independent of the sleeve position. Furthermore, the orientation of theingrowth interface may be independent from the axis of the extension1418 and the sleeve 1408. It will be appreciated that the method stepsapplicable to this arrangement are substantially as previously describedin connection with other similar configurations, and will not berepeated here.

Referring to FIGS. 53 and 54, a compliant fixation device 1500 forattaching an external prosthetic device 1590, such as an externalprosthesis or external prosthesis adapter, to a bone 1592 isillustrated. The fixation device 1500 includes a main body 1502 with acompliant portion 1512 that can be expanded and contracted as describedhereinabove in various embodiments. The compliant portion 1512 caninclude washer springs, accordion-like springs, helical springs, etc.,or other compliant structures as already disclosed. The main body 1502includes a bone tray 1504 at a first end 1503, and is coupled to anextension 1506 at a second end 1505. The main body 1502 and theextension 1506 can be modular components coupled to each other by knownmeans, including, for example, a Morse taper connection. In theexemplary embodiment of FIG. 53, the extension 1506 defines a male taper1507 received in a female taper 1509 of the main body 1502. The mainbody 1502 and the extension 1506 can also be integrally formed. The bonetray 1504 provides an abutment surface 1513 for engagement with the bone1592. The abutment surface 1513 can be flat or concave toward the bone1592 or have any other shape suitable for engagement with the bone 1592.The main body 1502 can include a plurality of apertures 1531 through theabutment surface 1513 for receiving fasteners 1533 to prevent rotationrelative to the bone 1592.

The fixation device can also include an anchor 1510 which can bemodularly or integrally connected to the compliant portion 1512. Theanchor 1510 can be attached to a cavity 1593 in the bone 1592 with crosspins or helical threads 1522 as described hereinabove in variousembodiments. The anchor 1510 can also be directly attached to the mainbody 1502. The main body 1502 can include a post 1550 threadably coupledwith the compliant portion 1512 through the bone tray 1513. As describedabove, an expansion rod can be provided for expanding the compliantportion 1512 relative to the main body 1502. The expansion rod can bethreadably coupled to the compliant portion 1502 to cause the compliantportion 1502 to expand while connected to the anchor 1510. Otherexpansion methods can also be used as described above.

The main body 1502 defines a first engagement surface 1530, which canbe, for example, in the form of a shoulder, and the extension 1506defines a second engagement surface 1532, which can be, for example, inthe form of a ring or cap, as illustrated in FIG. 53. The first andsecond engagement surfaces 1530, 1532 can be configured to constraint abone graft or other vascularized graft 1540 that is attached to the bone1592. In the exemplary application of FIG. 54, the fixation device 1500is attached to a distal femoral bone 1592, and the bone graft 1540 is aknee patella. It will be appreciated, that the graft 1540 can be adifferent vascularized graft depending on the particular application.The main body 1502, or at least a portion thereof can have a porous orother growth promoting coating.

The extension 1506 may include a second ring 1534 that includes sutureapertures 1535 for capturing the skin 1594 which is also sutured to thebone graft 1540. The first and second rings 1532, 1534 may be integrallyformed as a single cap, for example. In one aspect, the extension 1506can include a blind bore 1511 with internal threads 1537 for threadablyconnecting to the external prosthesis device 1590 by, for example, auniversal prosthesis adapter. In the event that the external prosthesisdevice 1590 needs to be replaced because or failure or changing needs,the external prosthesis device 1590 can be easily removed withoutdisturbing the skin or the bone fixation. Additionally, the blind bore1511 prevents contamination and an infection from reaching the skininteriorly.

It will be appreciated that any features of any of the embodimentsand/or method steps set forth herein are intended to be substituted,shared and/or moved among the various versions and methods involving theassembly. As an example, it will be appreciated that any of the threadedanchor bodies described herein may be substituted for cross-pinnedversions. Another contemplated arrangement involves the switching ofpositions of the compliant section and anchor, so that the anchor isthreaded or cross-secured to the near side of the compliant sectionrelative to the main body.

Yet another contemplated arrangement involves the ability of thecompliant section to be switchable between extension and compressionconditions, referring to the at-rest condition of the compliant sectionprior to engagement by a extension or compression rod, respectively. Inthe case of an extension compliant section, an extension rod expands orpulls the compliant section, such as by abutting a closed-ended aperturewithin the compliant section. In the case of a compression compliantsection, a compression rod having a head or knob passes from the endopposite the main body through an aperture through the anchor body andcompliant section to compress or push the already-expanded compliantsection to a lesser degree of expansion. Force is applied to thecompression version of compliant section by the knob or head against theend of the compliant section when the compression rod is threaded into athreaded recess in the main body. The present invention alsocontemplates the use of Belleville washers within a recess of a sleevedisposed integrally with or otherwise attached to the anchor body, as asubstitute for the compliant section. The Belleville washers arecompressed by applying force to a plate or other device to the endwasher such as by threading a compression rod with such a plate or otherdevice through the washer section from a side opposite the main body.Thus, it will be appreciated that several methods are contemplated forthe application of force in a compression or extension environment,using various compression and expansion implements, from eitherdirection relative to the main body of the assembly.

The foregoing discussion discloses and describes merely exemplaryarrangements of the present invention. One skilled in the art willreadily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention as defined in the following claims.

1. A fixation device for attaching an external prosthesis to a bone, thefixation device comprising a main body including a compliant portionoperable to be expanded and contracted, the main body having a first endoperable to be fixedly retained in the bone and a second end coupled toan extension configured for receiving the external prosthesis, whereinthe main body and the extension define respectively first and secondengagement surfaces configured for constraining a bone graft between thefirst and second engagement surfaces, wherein the main body is coupledto the extension by a Morse taper connection.
 2. The device of claim 1,wherein the main body includes a female taper receiving a male taper ofthe extension.
 3. A fixation device for attaching an external prosthesisto a bone, the fixation device comprising a main body including acompliant portion operable to be expanded and contracted, the main bodyhaving a first end operable to be fixedly retained in the bone and asecond end coupled to an extension configured for receiving the externalprosthesis, wherein the main body and the extension define respectivelyfirst and second engagement surfaces configured for constraining a bonegraft between the first and second engagement surfaces, wherein theextension includes internal threading for receiving the externalprosthesis.
 4. A fixation device for attaching an external prosthesis toa bone, the fixation device comprising a main body including a compliantportion operable to be expanded and contracted, the main body having afirst end operable to be fixedly retained in the bone and a second endcoupled to an extension configured for receiving the externalprosthesis, wherein the main body and the extension define respectivelyfirst and second engagement surfaces configured for constraining a bonegraft between the first and second engagement surfaces, wherein thefirst engagement surface is a superior shoulder of the main body.
 5. Afixation device for attaching an external prosthesis to a bone, thefixation device comprising a main body including a compliant portionoperable to be expanded and contracted, the main body having a first endoperable to be fixedly retained in the bone and a second end coupled toan extension configured for receiving the external prosthesis, whereinthe main body and the extension define respectively first and secondengagement surfaces configured for constraining a bone craft between thefirst and second engagement surfaces, wherein the second engagementsurface is a ring coupled to the extension.
 6. A fixation device forattaching an external prosthesis to a bone, the fixation devicecomprising a main body including a compliant portion operable to beexpanded and contracted, the main body having a first end operable to befixedly retained in the bone and a second end coupled to an extensionconfigured for receiving the external prosthesis, wherein the main bodyand the extension define respectively first and second engagementsurfaces configured for constraining a bone graft between the first andsecond engagement surfaces, wherein the extension is integral to themain body.
 7. A fixation device for attaching an external prosthesis toa bone, the fixation device comprising a main body including a compliantportion operable to be expanded and contracted, the main body having afirst end operable to be fixedly retained in the bone and a second endcoupled to an extension configured for receiving the externalprosthesis, wherein the main body and the extension define respectivelyfirst and second engagement surfaces configured for constraining a bonegraft between the first and second engagement surfaces, wherein theextension includes a plurality of suture apertures for attaching skin.8. A fixation device for attaching an external prosthesis to a bone, thefixation device comprising a main body including a compliant portionoperable to be expanded and contracted, the main body having a first endoperable to be fixedly retained in the bone and a second end coupled toan extension configured for receiving the external prosthesis, whereinthe main body and the extension define respectively first and secondengagement surfaces configured for constraining a bone graft between thefirst and second engagement surfaces, wherein the main body includes abone tray operable to engage a prepared bone surface.
 9. The device ofclaim 8, wherein the main body further includes a post attached to thebone tray.
 10. The device of claim 9, wherein the post is threadablycoupled to the compliant portion.
 11. The device of claim 9, whereinupon rotating the post, the compliant portion is expanded to a desiredcondition of expansion after the main body is attached to the bone. 12.The device of claim 8, wherein the compliant portion is directlyattached to the bone tray.
 13. A fixation device for attaching anexternal prosthesis to a bone, the fixation device comprising a mainbody including a compliant portion operable to be expanded andcontracted, the main body having a first end operable to be fixedlyretained in the bone and a second end coupled to an extension configuredfor receiving the external prosthesis, wherein the main body and theextension define respectively first and second engagement surfacesconfigured for constraining a bone graft between the first and secondengagement surfaces, wherein the main body further includes a pluralityof apertures for receiving bone fasteners.
 14. A fixation device forattaching an external prosthesis to a bone, the fixation devicecomprising a main body including a compliant portion operable to beexpanded and contracted, the main body having a first end operable to befixedly retained in the bone and a second end coupled to an extensionconfigured for receiving the external prosthesis, wherein the main bodyand the extension define respectively first and second engagementsurfaces configured for constraining a bone araft between the first andsecond engagement surfaces, wherein the main body is attached to thebone by an anchor.
 15. The device of claim 14, wherein the compliantportion is integral with the anchor.
 16. The device of claim 15, whereinthe compliant portion is shaped as a helical spring.
 17. A fixationdevice for attaching an external prosthesis to a bone, the fixationdevice comprising a main body including a compliant portion operable tobe expanded and contracted, the main body having a first end operable tobe fixedly retained in the bone and a second end coupled to an extensionconfigured for receiving the external prosthesis, wherein the main bodyand the extension define respectively first and second engagementsurfaces configured for constraining a bone graft between the first andsecond engagement surfaces, wherein the compliant portion includesspring washers.
 18. A fixation device for attaching an external kneeprosthesis to a distal femoral bone having an attached patella, thefixation device comprising: a main body operable to engage a preparedfemoral surface, the main body having a superior shoulder; an extensioncoupled to the main body with a taper to taper connection, the extensionincluding a inferior ring, the inferior ring and the superior shoulderconfigured to constraint the patella therebetween; an anchor coupled tothe main body and operable to be fixedly retained within the femoralbone; and a compliant portion operable to be expanded and contracted,the compliant portion disposed between the body and the anchor.
 19. Thedevice of claim 18, wherein the main body further includes a femoraltray operable to engage the prepared femoral surface.
 20. The device ofclaim 18, wherein the compliant portion is integral with the anchor. 21.The device of claim 18, wherein the compliant portion is shaped as ahelical spring.
 22. The device of claim 18, wherein the anchor includesexternal helical threads operable to fixedly attach the anchor within acavity formed within the femoral bone.
 23. The device of claim 18,wherein the main body includes a threaded post operable to threadablypass through the femoral tray.
 24. The device of claim 23, wherein thepost is threadably attached to the compliant portion and is operable toadjust a force applied to the compliant portion.
 25. A compliantfixation device for attaching an external prosthesis to a bone having anattached bone graft, the fixation device comprising a compliant portion,first and second engagement surfaces configured for constraining theattached bone graft between the first and second engagement surfaces,and an extension including a bore for receiving a portion of theexternal prosthesis, the fixation device configured for receiving anexternal prosthesis at one end, wherein the extension includes a Morsetaper connection.
 26. The compliant fixation device of claim 25, whereinthe bone is a distal femur with an attached patella, and the first andsecond engagement surfaces are configured to retain the patella.
 27. Thecompliant fixation device of claim 26, wherein the second engagementsurface is a patella cap.
 28. The compliant fixation device of claim 25,wherein the extension is modularly coupled to the fixation device. 29.The compliant fixation device of claim 25, further comprising an anchorcoupled to the compliant portion.
 30. A compliant fixation device forattaching an external prosthesis to a bone having an attached bonegraft, the fixation device comprising a compliant portion, first andsecond engagement surfaces configured for constraining the attached bonegraft between the first and second engagement surfaces, and an extensionincluding a bore for receiving a portion of the external prosthesis, thefixation device configured for receiving an external prosthesis at oneend, wherein the extension includes a ring having suture apertures forcapturing skin.